\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}



\newcommand\invisiblesection[1]{%
  \refstepcounter{section}%
  \addcontentsline{toc}{section}{\protect\numberline{\thesection}#1}%
  \sectionmark{#1}}

\newif\ifquoteopen
\catcode`\"=\active % lets you define `"` as a macro
\DeclareRobustCommand*{"}{%
   \ifquoteopen
     \quoteopenfalse ''%
   \else
     \quoteopentrue ``%
   \fi
}



\usepackage[]{hyperref}
\hypersetup{
    pdftitle={},
    pdfauthor={},
    pdfsubject={},
    pdfkeywords={},
    bookmarksnumbered=true,
    bookmarksopen=true,
    bookmarksopenlevel=1,
    colorlinks=false,
    pdfstartview=Fit,
    pdfpagemode=UseOutlines,    % this is the option you were lookin for
    pdfpagelayout=TwoPageRight
}



\usepackage{multicol}

\usepackage[paperwidth=6.21in,paperheight=8.28in,margin=0.5in]{geometry}

\usepackage{titlesec}
\titleformat{\section}{\normalfont\Large\bfseries}{}{0pt}{}
\titleformat{\subsection}{\normalfont\Large\bfseries}{}{0pt}{}

\usepackage{fancyhdr}

\pagestyle{fancy}
\renewcommand{\sectionmark}[1]{\markboth{#1}{}} % set the \leftmark

\usepackage[dvipsnames]{xcolor}

\renewcommand{\headrule}{\hbox to\headwidth{%
  \color{gray}\leaders\hrule height \headrulewidth\hfill}}



\usepackage{refcount}
\usepackage{etoolbox}
\usepackage{pgffor}
\usepackage{lastpage}

% Header
\fancyhf{}
\fancyhead[L]{
    \color{gray}{
    \scriptsize{
        \textit{~~date~~}}}} % predefined ()
\fancyhead[R]{
    \color{gray}{
    \scriptsize{
        \thepage of \pageref{LastPage}}}} % 1. sectionname
\fancyhead[C]{
    \color{gray}{
    \scriptsize{
        \textbf{\leftmark}}}}
\fancypagestyle{plain}{
    \fancyhf{}
    \renewcommand{\headrulewidth}{0pt}
}

% Footer (none)
\fancyfoot{}

\headheight 0.5in \headsep 10pt

\usepackage[all]{nowidow}

\setlength{\columnsep}{0.33in}

\titleformat{\subsection}[display]
  {}{}{10pt}{\Huge}

\usepackage{lastpage}

\begin{document}

%\tableofcontents
%\newpage

\invisiblesection{~~category~~}

\subsection{~~title~~}

\textit{By ~~author~~, ~~org~~}

\begin{multicols*}{2}

~~body~~

\end{multicols*}
\newpage

\end{document}