\documentclass[12pt]{book}
\usepackage[english]{babel} %%%%%%%%%%%%%%%%%% (EDIT LANGUAGE)
\usepackage{Custom} %%%%%%%%%%%%%%%%%% (EDIT NAMES)
\usepackage{AuxiliaryFiles/AuxiliaryFiles} %%%%%%%%%%%%%%%%%% (DO NOT EDIT)
\usepackage{Custom-2} %%%%%%%%%%%%%%%%%% (EDIT)
\begin{document}
\input{Structure/Title/Title.tex} %%%%%%%%%%%%%%%%%% (EDIT TITLEPAGE)
\input{Structure/Title/Title-2.tex} %%%%%%%%%%%%%%%%%% (SECOND VERSION)
\newcommand\IndexYes{1}
%%%%%%%%%%%%%%%%%% (IF A TABLE OF CONTENTS IS NOT NEEDED, CHANGE 1 TO 0)
\input{AuxiliaryFiles/Frontmatter} %%%%%%%%%%%%%%%%%% (DO NOT EDIT)
\input{Structure/Introduction} %%%%%%%%%%%%%%%%%% (EDIT INTRODUCTION)
\input{Structure/Errata} %%%%%%%%%%%%%%%%%% (EDIT ERRATA)
\input{AuxiliaryFiles/Mainmatter} %%%%%%%%%%%%%%%%%% (DO NOT EDIT)
\input{Structure/Chapter1} %%%%%%%%%%%%%%%%%% (EDIT CHAPTERS)
\input{Structure/Chapter2}
\input{Structure/Chapter3}
\begin{appendices} %%%%%%%%%%%%%%%%%% (COMMENT IF NOT NEEDED)
\input{AuxiliaryFiles/Appendices} %%%%%%%%%%%%%%%%%% (DO NOT EDIT)
\input{Structure/Appendices/Appendix-A}
\end{appendices}
\input{AuxiliaryFiles/Backmatter} %%%%%%%%%%%%%%%%%% (DO NOT EDIT)
\end{document}