It did not work in Firefox 95.02 when I first installed it, from PF & PDF website. Could not get the icon to appear in the Menu Bar even after trying what Support suggested.
Then I decided to uninstall Firefox completely from Windows. Was asked if I wanted to try a "Refresh" first. Did that, and all extensions were eliminated. Then downloaded PF & PDF extension thru Firefox Add-Ons, and IT WORKED!. The icon came up on the Menu Bar just as it should.
Apparently there is a difference in where you install the PF & PDF extension from. I wonder why? But since it now works, I am very happy.
Thanks, Support Guy!