Altium Designer does not recognize Library of PI Adapter PCB

Many greetings from Berlin, Germany.

I am running into a problem while gernerating Gerber files for the PI adapter. When loading the Altium project (Pi Adapter revision 1.1), I am getting the following error message:

Later on, the BOM is showing some weird characters. I am not sure if my PCB service can read this. Any idea if this is even relevant?
I am using Altium Designer 19.1.7 (Build 138), fully licensed.

Best wishes,