Hi

Have you tried to find and edit PGP file, as described here:
https://forums.autodesk.com/t5/autocad-for-mac-forum/unable-to-modify-pgp-autocad-lt-2016-mac/m-p/87...

"The default PGP file can also be opened by launching Finder, pressing and holding Option, and clicking Go Library. In the Finder window, navigate to Application Support/Autodesk/Roaming/<product name>/<version>/<language>/Support and double-click acad.pgp (or acadlt.pgp for AutoCAD LT) to edit the file. If prompted for an application to use, select TextEdit."