Can't start Duplicati on Qnap - myqnapcloud Link conflict

I use Duplicati an 2 ubuntu 20.04 servers and I#m really happy how nice and easy it works.

Now i figured out how to instal on Qnap and it would be great to use Duplicati for Backup on external onedrive or … service!

Installation went without any issues.

But starting the App on the Qnap Interface a error message appears:
“This service does not support myQNAPcloud Link service.”

Any idea what to do?

Somewhere I saw a note to use portforwarding? But i don’t nknow how to configure that to open the channel for Duplicati?

Thanks for your help…
all the best