I would appreciate some hints about the preamble. For instance for font/background colors.
The add-in doesn't offer you the possibility to change fonts and colors. Since this is an add-in for a Microsoft package, then you cause the built-in options to change the color or the background (eg. Word, Exce, Powerpoint).
I've seen various images with the plug-in and it confirms what I'm saying.
For additional info, use the website: https://code.google.com/archive/p/powerpointtools/wikis/PowerPointLaTeX.wiki