Port :5002 not reachable (Jam App)

I am running Umbrel 1.1 on a Raspberry Pi 5 with 8GB. 2TB SSD.
I have installed the Jam App that uses Port 5002 but when I click the app, my browser tells me that he cannot connect to Port 5002 and I cannot open the app.

All other apps works well without any issues.

What is the problem here?