Letter paper is 215.9 x 279.4
A4 paper is 210 x 297

So when you go to print you may have slight problems with page layout when printing A4 or exporting to PDF. The fix is as follows:

In each Latex template find the line near the top that has the letterpaper keyword
\usepackage[letterpaper,top=2cm,bottom=1.5cm,left=1.1cm,right=1.5cm]{geometry}

Change it to be a4paper
\usepackage[a4paper,top=2cm,bottom=1.5cm,left=1.1cm,right=1.5cm]{geometry}