Microsoft fonts are the reason you cannot rename. Instead of fully instaling the fonts are being shared .  The location of these shares are pretty deep:

..Mas90\Home\TINYMCE\JS\TINYMCE\LIGHTGRAY\FONTS\TINYMCE.TTF  and TINYMCE-SMALL.TTF

As for your instial error I have nto experienced. it.

Had something similar happen. New installation of Sage 100 2020, applied PU 1 and then installed PR 2.21.

As PR 2.21 installation was being finalized, we received an InstallShield Wizard Error: "Finalize failed with the following error:", with just an OK button. Clicked OK and received: "Error Encountered | File 'PR_EmployeePDFEDeliveryLog' not found."

Info: "Error 12 SY_PII.pvc Line 326". I reinstalled PR 2.21 and it went through without errors. We could then access 2020 and migrate data. After migration, however, when we tried to login to Sage we received the following:
"An error occurred converting personally identifiable information. An administrator must login to restart the conversion process."

That reminded me of the old message about an administer maintaining the system so I looked, and sure enough there was an "InstLock.txt" in the Home folder. Of course first I logged in as the Administrator and attempted to convert company data, no luck there.

Then we received the pop-up box which seemed to require us to change the PII Encryption Key.

Eventually we were able to bypass all the errors and get back to converting data.