commutative diagram in special shape

Question

I wish to draw the following diagram, but I do not know how to draw it correctly, may you please help me

Answer 1

\documentclass{article}
\usepackage{tikz-cd}
\usepackage{amsmath}
\begin{document}
\[
\begin{tikzcd}[row sep=1.4cm,column sep=1.4cm]
D_1\arrow[r,"\varepsilon_1"] \arrow[dr,swap,"\forall\delta_1"]& D_1*D_2
\arrow[d,"\exists!f"] & 
\arrow[l,"\varepsilon_1",swap] \arrow[dl,"\forall\delta_2"]D_2\\
&  D& 
\end{tikzcd}
\]
\end{document}