I have tried to compile the following on my own MAC machine through both my text editor and the latexit app, as well as on sharelatex. On my machine I have to quit after a long time, and sharelatex timed out. Im not sure exactly why this isnt quitting with an error or something. I copied and pasted an example from the tikz documentation and put it in a sample beamer slide.
\documentclass{beamer}
% Note - to make this an article/handout we would use:
% \documentclass{article}
% \usepackage{beamerarticle}
\usepackage{pgfpages}
\usepackage{blindtext}
\usepackage{tikz}
\blindmathtrue
\usepackage{multicol}
% \setbeameroption{show notes on second screen}
\usetheme[progressbar=frametitle]{metropolis} % Use metropolis theme
% \setbeamertemplate{frame numbering}[none]
\metroset{block=fill}
\setbeamercovered{transparent=15}
\usepackage{amsmath,amssymb,amsthm,mathrsfs,bbm,bm}
\usepackage{graphicx,subcaption,float,enumerate}
\title[short title]{Functions Testing}
\subtitle{Lecture 1}
\date{}
\author{}
\institute{School}
\begin{document}
\maketitle
% \setbeameroption{show notes on second screen}
\begin{frame}[Tea]
\begin{tikzpicture}[thick,help lines/.style={thin,draw=black!50}]
\def\A{\textcolor{input}{$A$}} \def\C{\textcolor{output}{$C$}} \def\E{$E$}
\colorlet{input}{blue!80!black} \colorlet{triangle}{orange}
\def\B{\textcolor{input}{$B$}} \def\D{$D$}
\colorlet{output}{red!70!black}
\coordinate [label=left:\A]
(A) at ($ (0,0) + .1*(rand,rand) $); \coordinate [label=right:\B] (B) at ($ (1.25,0.25) + .1*(rand,rand) $);
\draw [input] (A) -- (B);
\node [name path=D,help lines,draw,label=left:\D]
\node [name path=E,help lines,draw,label=right:\E]
(D) at (A) [circle through=(B)] {};
(E) at (B) [circle through=(A)] {};
\path [name intersections={of=D and E,by={[label=above:\C]C}}];
\draw [output] (A) -- (C) -- (B);
\foreach \point in {A,B,C} \fill [black,opacity=.5] (\point) circle (2pt);
\begin{pgfonlayer}{background} \fill[triangle!80] (A) -- (C) -- (B) -- cycle;
\end{pgfonlayer}
\node [below right, text width=10cm,align=justify] at (4,3) { \small\textbf{Proposition I}\par \emph{To construct an \textcolor{triangle}{equilateral triangle} on a given \textcolor{input}{finite straight line}.} \par\vskip1em Let \A\B\ be the given \textcolor{input}{finite straight line}.
}; \end{tikzpicture}
\end{frame}
\end{document}
(D) at (A) [circle through=(B)] {};
two lines up. Also, I can't see where you are loading tikz and the relevant libraries.\node [name path=D,help lines,draw,label=left:\D]