Code for 2 column pdf in Rmarkdown ceases to work when moving between machines

Hello:

I am trying to produce a pdf with a 2 column format. I found online a bit of code that allows one to "trick" Rmarkdown into producing two column pdfs.

  \newcommand{\hideFromPandoc}[1]{#1}
  \hideFromPandoc{
    \let\Begin\begin
    \let\End\end

However, in moving from one machine to another, the code does not work. The error I get is:

! Undefined control sequence.
l.106 \Begin
            {multicols}{2}

my complete header information is below. Any advice on why the code would work on one Windows 10 machine and not another would be helpful. RStudio version is 1.1.442. R version is 3.5.1.

Thanks
Amer (new to markdown and to R)


---
title: "`blah"
author: "Blah"
output: 
  pdf_document:
    latex_engine: xelatex
    fig_caption: yes
    keep_tex: yes
fontsize: 8pt
geometry: "left=1.5cm,right=1cm,top=2cm,bottom=2.2cm"
header-includes: \usepackage{fancyhdr} 
  \usepackage{graphicx} 
  \usepackage{eurosym} 
  \usepackage{booktabs,xcolor} \pagestyle{fancy}
  \rhead{October 2018}
  \rfoot{}  
  \lfoot{\includegraphics[width=19.5cm]{footerpdf.pdf}} 
  \fancypagestyle{plain}{\pagestyle{fancy}} 
  \pagenumbering{gobble}
  \usepackage{pagecolor}
  \pagecolor{white}
  \usepackage{librebaskerville}
  \usepackage[fontsize=8pt]{scrextend}
  \usepackage{float}
  \restylefloat{table}
  \usepackage{xcolor}
  \usepackage{multicol}
  \newcommand{\hideFromPandoc}[1]{#1}
  \hideFromPandoc{
    \let\Begin\begin
    \let\End\end
  }
  \usepackage{caption}
  \captionsetup{skip=0pt}
---
\Begin{multicols}{2}

blah.


\End{multicols}