Trouble positioning the date in a complex titlepage

Question

I have got the following template online (with some searching) and basically my problem is how to set the date close to the lower part of the title page.

The code I used to get the output above follows below:

\documentclass[letterpaper]{article}
\usepackage{babel,titling,float,tikz,amsmath,cancel,amsbsy,amsfonts,graphicx,adjustbox,epigraph}
\renewcommand\epigraphflush{flushright}
\renewcommand\epigraphsize{\normalsize}
\setlength\epigraphwidth{0.7\textwidth}
\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}
\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{it}{0.5in}
\makeatletter

\def\printauthor{%

    {\large @author}}

\makeatother
\author{%
    \normalsize{Rodrigo Domingues (99390)\
    Departamento de Matemática \
    Universidade de Aveiro \
    \texttt{rodrigo.domingues@ua.pt}\vspace{20pt} \
    Beatriz Teixeira (99366) \
    Departamento de Matemática \
    Universidade de Aveiro \
    \texttt{oteuemail@ua.pt}}
    }
% The following code is borrowed from: https://tex.stackexchange.com/a/86310/10898
\newcommand\titlepagedecoration{%
\begin{tikzpicture}[remember picture,overlay,shorten >= -10pt]
\coordinate (aux1) at ([yshift=-15pt]current page.north east);
\coordinate (aux2) at ([yshift=-410pt]current page.north east);
\coordinate (aux3) at ([xshift=-4.5cm]current page.north east);
\coordinate (aux4) at ([yshift=-150pt]current page.north east);
\begin{scope}[titlepagecolor!40,line width=12pt,rounded corners=12pt]
\draw
  (aux1) -- coordinate (a)
  ++(225:5) --
  ++(-45:5.1) coordinate (b);
\draw[shorten <= -10pt]
  (aux3) --
  (a) --
  (aux1);
\draw[opacity=0.6,titlepagecolor,shorten <= -10pt]
  (b) --
  ++(225:2.2) --
  ++(-45:2.2);
\end{scope}
\draw[titlepagecolor,line width=8pt,rounded corners=8pt,shorten <= -10pt]
  (aux4) --
  ++(225:0.8) --
  ++(-45:0.8);
\begin{scope}[titlepagecolor!70,line width=6pt,rounded corners=8pt]
\draw[shorten <= -10pt]
  (aux2) --
  ++(225:3) coordinate[pos=0.45] (c) --
  ++(-45:3.1);
\draw
  (aux2) --
  (c) --
  ++(135:2.5) --
  ++(45:2.5) --
  ++(-45:2.5) coordinate[pos=0.3] (d);

\draw 
  (d) -- +(45:1);
\end{scope}
\end{tikzpicture}%
}
\date{8 de julho, 2022}
\begin{document}
\begin{titlepage}
\noindent
\titlefont Projeto 1 \

           \small Otimização em Redes e Não Linear \par 
\vspace{.5cm}
\epigraph{If the system exhibits a structure which can be represented by a mathematical equivalent, called a mathematical model, and if the objective can be also so quantified, then some computational method may be evolved for choosing the best schedule of actions among alternatives. Such use of mathematical models is termed mathematical programming.}%
{\textit{"Linear Programming and Extensions", 2016}\ \textsc{G. Dantzig}}
\null\vfill
\vspace{1cm}
\noindent
\vfill
\hfill
\begin{minipage}{0.50\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage}
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{125pt}
\end{minipage}
\begin{center}
    \textbf{\thedate}
\end{center}
\titlepagedecoration
\end{titlepage}

My desired output follow below:

Answer 1

An analysis, no complete solution:

• only a few packages were needed to render this titlepage
• included \usepackage[showframe]{geometry} to see current settings
• had to manually set the date, as a workaround
• \end{document} was missing in the copied source
• rest seems to be fine: one way to do it

So from the frames drawn the date already is "at the bottom".

Suggestions:

• move date to footer
• OR remove footer and expand layout as needed, i.e. the textheight
• see documentation at ctan geometry for details (https://ctan.org/pkg/geometry)

\documentclass[letterpaper]{article}
%\usepackage{babel,titling,float,tikz,amsmath,cancel,amsbsy,amsfonts,graphicx,adjustbox,epigraph}
\usepackage{epigraph, adjustbox, tikz}% <<< only what's needed here
\usepackage[showframe]{geometry}% <<< to show frames
\renewcommand\epigraphflush{flushright}
\renewcommand\epigraphsize{\normalsize}
\setlength\epigraphwidth{0.7\textwidth}
\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}
\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{it}{0.5in}
\makeatletter

\def\printauthor{%

    {\large @author}}

\makeatother
\author{%
    \normalsize{Rodrigo Domingues (99390)\
    Departamento de Matemática \
    Universidade de Aveiro \
    \texttt{rodrigo.domingues@ua.pt}\vspace{20pt} \
    Beatriz Teixeira (99366) \
    Departamento de Matemática \
    Universidade de Aveiro \
    \texttt{oteuemail@ua.pt}}
    }
% The following code is borrowed from: https://tex.stackexchange.com/a/86310/10898
\newcommand\titlepagedecoration{%
\begin{tikzpicture}[remember picture,overlay,shorten >= -10pt]
\coordinate (aux1) at ([yshift=-15pt]current page.north east);
\coordinate (aux2) at ([yshift=-410pt]current page.north east);
\coordinate (aux3) at ([xshift=-4.5cm]current page.north east);
\coordinate (aux4) at ([yshift=-150pt]current page.north east);
\begin{scope}[titlepagecolor!40,line width=12pt,rounded corners=12pt]
\draw
  (aux1) -- coordinate (a)
  ++(225:5) --
  ++(-45:5.1) coordinate (b);
\draw[shorten <= -10pt]
  (aux3) --
  (a) --
  (aux1);
\draw[opacity=0.6,titlepagecolor,shorten <= -10pt]
  (b) --
  ++(225:2.2) --
  ++(-45:2.2);
\end{scope}
\draw[titlepagecolor,line width=8pt,rounded corners=8pt,shorten <= -10pt]
  (aux4) --
  ++(225:0.8) --
  ++(-45:0.8);
\begin{scope}[titlepagecolor!70,line width=6pt,rounded corners=8pt]
\draw[shorten <= -10pt]
  (aux2) --
  ++(225:3) coordinate[pos=0.45] (c) --
  ++(-45:3.1);
\draw
  (aux2) --
  (c) --
  ++(135:2.5) --
  ++(45:2.5) --
  ++(-45:2.5) coordinate[pos=0.3] (d);

\draw 
  (d) -- +(45:1);
\end{scope}
\end{tikzpicture}%
}
\date{8 de julho, 2022}
\begin{document}
\begin{titlepage}
\noindent
\titlefont Projeto 1 \

           \small Otimização em Redes e Não Linear \par 
\vspace{.5cm}
\epigraph{If the system exhibits a structure which can be represented by a mathematical equivalent, called a mathematical model, and if the objective can be also so quantified, then some computational method may be evolved for choosing the best schedule of actions among alternatives. Such use of mathematical models is termed mathematical programming.}%
{\textit{"Linear Programming and Extensions", 2016}\ \textsc{G. Dantzig}}
\null\vfill
\vspace{1cm}
\noindent
\vfill
\hfill
\begin{minipage}{0.50\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage}
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{125pt}
\end{minipage}
\begin{center}
%    \textbf{\thedate}% <<< didn't work
    \textbf{8 de julho, 2022}% <<< workaround
\end{center}
\titlepagedecoration
\end{titlepage}
\end{document}% was missing (!)

Answer 2

(1) Load the package geometry.

(2) Before the titlepage add \newgeometry{bottom=0.5cm} to expand the (default) bottom margin of the page.

(3) Add vertical space before the date,

(4) Use \restoregeometry to restore the margin of the document.

\documentclass{article}
\usepackage{geometry}% added <<<<<<<<<<
\usepackage{babel,titling,float,tikz,amsmath,cancel,amsbsy,amsfonts,graphicx,adjustbox,epigraph}
\renewcommand\epigraphflush{flushright}
\renewcommand\epigraphsize{\normalsize}
\setlength\epigraphwidth{0.7\textwidth}
\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}
\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{it}{0.5in}
\makeatletter

\def\printauthor{%

    {\large @author}}

\makeatother
\author{%
    \normalsize{Rodrigo Domingues (99390)\
        Departamento de Matemática \
        Universidade de Aveiro \
        \texttt{rodrigo.domingues@ua.pt}\vspace{20pt} \
        Beatriz Teixeira (99366) \
        Departamento de Matemática \
        Universidade de Aveiro \
        \texttt{oteuemail@ua.pt}}
}
% The following code is borrowed from: https://tex.stackexchange.com/a/86310/10898
\newcommand\titlepagedecoration{%
    \begin{tikzpicture}[remember picture,overlay,shorten >= -10pt]
    \coordinate (aux1) at ([yshift=-15pt]current page.north east);
    \coordinate (aux2) at ([yshift=-410pt]current page.north east);
    \coordinate (aux3) at ([xshift=-4.5cm]current page.north east);
    \coordinate (aux4) at ([yshift=-150pt]current page.north east);

    \begin{scope}[titlepagecolor!40,line width=12pt,rounded corners=12pt]
        \draw
        (aux1) -- coordinate (a)
        ++(225:5) --
        ++(-45:5.1) coordinate (b);
        \draw[shorten &lt;= -10pt]
        (aux3) --
        (a) --
        (aux1);
        \draw[opacity=0.6,titlepagecolor,shorten &lt;= -10pt]
        (b) --
        ++(225:2.2) --
        ++(-45:2.2);
    \end{scope}
    \draw[titlepagecolor,line width=8pt,rounded corners=8pt,shorten &lt;= -10pt]
    (aux4) --
    ++(225:0.8) --
    ++(-45:0.8);
    \begin{scope}[titlepagecolor!70,line width=6pt,rounded corners=8pt]
        \draw[shorten &lt;= -10pt]
        (aux2) --
        ++(225:3) coordinate[pos=0.45] (c) --
        ++(-45:3.1);
        \draw
        (aux2) --
        (c) --
        ++(135:2.5) --
        ++(45:2.5) --
        ++(-45:2.5) coordinate[pos=0.3] (d);   
        \draw 
        (d) -- +(45:1);
    \end{scope}
\end{tikzpicture}%

}
\date{8 de julho, 2022}
\begin{document}
    \newgeometry{bottom=0.5cm} % geometry of the title page <<<<<
\begin{titlepage}

    \noindent
    \titlefont Projeto 1 \\  
    \small Otimização em Redes e Não Linear \par 
    \vspace*{.5cm}
    \epigraph{If the system exhibits a structure which can be represented by a mathematical equivalent, called a mathematical model, and if the objective can be also so quantified, then some computational method may be evolved for choosing the best schedule of actions among alternatives. Such use of mathematical models is termed mathematical programming.}%
    {\textit{&quot;Linear Programming and Extensions&quot;, 2016}\\ \textsc{G. Dantzig}}
    \null\vfill
    \vspace*{1cm}
    \noindent
    \vfill
    \hfill
    \begin{minipage}{0.50\linewidth}
        \begin{flushright}
            \printauthor
        \end{flushright}
    \end{minipage}
    \begin{minipage}{0.02\linewidth}
        \rule{1pt}{125pt}
    \end{minipage}      

    \vfill%% &lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;
    \begin{center}
        \textbf{\thedate}
    \end{center}

    \titlepagedecoration%
\end{titlepage}


\restoregeometry    % ends the  geometry of the titlepage <<<<<<<<<<<<<<<
\end{document}