Ring intercom: App setup workflow hangs after successful ring and door opening test

I installed my Ring intercom to my Ritto 7630/x0 Twinbus system. Then started the setup workflow in Ring App. The workflow goes through the ringer and door opener test, both tests successful, what means the integration of Ring intercom and Twinbus is working. But then the app hangs in next step. Don't know what this step does. I can't finish the setup. What i can do?