Answer:
Please check whether you have started the licensed main program RFEM 5 / RSTAB 8 or opened the "viewer" by mistake. This viewer is only used to view files. It is license-free.
Wenn Sie Dateien erstellen wollen, dann müssen Sie das lizenzierte Hauptprogramm starten. If the link does not exist anymore, you can copy the link to the viewer and then remove the "/viewer" addition in the properties.