Hi Reino
I believe this issue was caused by the customer updating to macOS Catalina after the new server was installed. Removing all instances of Standard ERP server applications, and then reinstalling the new Standard ERP server will solve this problem.
In regard to a mac server "cheat sheet" we unfortunately do not have one, however please see the below links to our system admin basic and advanced manuals as they do cover much of this setup.
https://www.hansaworld.com/en/university/booking/courses/global/HW_SYS
https://www.hansaworld.com/en/university/booking/courses/global/HW_SYS2
Best Regards,
HansaWorld Support