Combining Files - Works on an Administrative Account but not a regular user

So, I have a weird thing happening.  Our users with no admin privileges are unable to combine files into a PDF format.  I logged into the same PC as the regular user, and was able to successfully combine 500 files into a PDF format.  The settings for the Add-in "PDF Maker" are the same for both admin and regular users.  What could be causing this issue?  We did just update from Server 2012 to 2019.  

I can't figure it out.