I'm required to have my dissertation in Times New Roman. I'm using LuaLaTeX because it lets me use figures which are too big for the usual compiler. I've tried several ways to change the font:
\usepackage{times}
was already in the template provided, but doesn't seem to do anything (the document appears in the normal LaTeX font).
\usepackage{fontspec}
\setmainfont{Times New Roman}
gives me undefined control sequence errors.
EDIT to give the whole code: My document is now like this:
\documentclass[10pt, twocolumn]{revtex4} % Font size (10,11 or 12pt) and column number (one or two).
\usepackage{fontspec}
%\setmainfont{Times New Roman}
\setmainfont{times}[
Extension = .ttf ,
BoldFont = *bd ,
ItalicFont = *i ,
BoldItalicFont = *bi
]
\usepackage[a4paper, left=1.85cm, right=1.85cm,
top=1.85cm, bottom=1.85cm]{geometry} % Defines paper size and margin length
%%%%% Document %%%%%
\begin{document}
Hello 123.
\end{document}
This gives a PDF in Times New Roman but with lots of Undefined Control Sequence Errors (none of which seem to be particularly helpful) and the top of the PDF looks like the picture below.

The log file is here: https://drive.google.com/file/d/1e9IwV-Nmbza2UDfbFEDmv3xarpbJrfOB/view?usp=sharing
Am I doing something wrong - is there a simple way to change the font type that I'm missing? Thanks in advance.
\setmainfont{Times New Roman}should normally work, if you have the font. – Ulrike Fischer Mar 17 '20 at 14:19\setmainfont{Times New Roman}gives the same error as above. When you say if I have the font - it's installed on my system, do I need to install it separately for this to work? – TIF Mar 17 '20 at 14:24\usepackage{times}and only used\setmainfont{Times New Roman}without specifying anything extra in the square brackets? – TivV Mar 17 '20 at 14:27\documentclassI used above, thenusepackage{fontspec},\setmainfont{Times New Roman}, then\begin{document}. – TIF Mar 17 '20 at 14:31