documentclass[10pt,final]{scrbook}

usepackage{titletoc} % modify toc title
usepackage{lipsum} % dummy text
usepackage{anyfontsize} % change fontsize
usepackage{tocloft} % design toc
usepackage{framed, xcolor}
usepackage[english,ngerman]{babel}
usepackage[latin1]{inputenc}
usepackage[T1]{fontenc}
usepackage{times}
usepackage{helvet}
usepackage{endnotes}
usepackage{titlesec}
usepackage[hyphens]{url}
usepackage{multicol}
usepackage[colorlinks=false, pdfborder={0 0 0}]{hyperref}
urlstyle{same}


addtocaptionsngerman{renewcommand{contentsname}{normalfont{Contents}}}
% section itshape
titleformat*{section}{itshape}
titleformat*{subsection}{itshape}
titlespacing*{subsection}{0cm}{0.84cm}{0.42cm}
titlespacing*{section}{0cm}{0.84cm}{0.42cm}
% Spacing between chapter and author
titlespacing*{chapter}{0cm}{0.84cm}{0.42cm}
%%% Chapter style
titleformat{chapter}[display]
  {normalfont}{chaptertitlename thechapter}{12pt}{Large}

% Display chapters in the Table of Contents
titlecontents{chapter}
  [0pt]% Left margin, optional
  {}% Code insertet above
  {mdseries}% Numbered-entryformat
  {mdseries}% Numberless-format
  {contentspage} % add dotfill and pagenumber, and some vertical space between entries

% Custom command to keep the author on the same page of chaptertitle, and above it.
newcommand{chapterAndAuthor} [2]{
 % #1: Author
 % #2: Chaptertitle
clearpage%
    % Minipage to keep the author and chaptertitle on same page
    noindentbegin{minipage}{textwidth}
        % Set the author style
        {selectfontfontsize{12}{14} itshape{#1}}
        % Bring the chaptertitle closer to the authortitle
        vspace{-3baselineskip}
         % Add an entry to the Table of Contents, with the name of the author in emph and the chapter title
  addcontentsline{toc}{chapter}{texorpdfstring{normalfont #1vspace{1ex}newline
    % For long chapter titles using a parbox
    hspace*{1em}protectparbox[b]{textwidth}{#2 dotfill}}{#2}}
  % Print the chapter
        chapter*{#2}
    end{minipage}
    }


% space between table of contents
setlengthcftparskip{0.21cm}
setlengthcftbeforesecskip{10pt}
setlengthcftaftertoctitleskip{10pt}
%pagestyle%
usepackage[paperheight=21.0cm,paperwidth=13.5cm,twoside,textwidth=10.3cm,textheight=16.3cm,nohead,pdftex]{geometry}
pagestyle{plain}

begin{document}
tableofcontents

clearpage

chapterAndAuthor{The name of the first author, The name of second author and The name of the third author}{Test Chapter One Test Chapter One Test Chapter One Test Chapter One Test Chapter One Test Chapter One Test Chapter One}
lipsum[1-4]
vspace{0.84cm}
subsection*{Subheading1 without indentation}
lipsum[1-4]
subsection*{Subheading2 without indentation}
lipsum[1-2]
subsection*{Subheading3 without indentation}
lipsum[1-2]
chapterAndAuthor{The name of the second author}{Test Chapter Two}
lipsum[1-5]

end{document}