Ubuntu settings for online account URL (Server Adress)

I am running a NCP at home. I have Ubuntu as OS on my client computer. But in the settings of Ubuntu i can not figure out the correct URL for the online account settings. On the ff browser and android the cloud is running like a charm.
I tried so many URL combinations like:
and many more

It always results in Unable to access USERNAME@xxx.xx not a WebDAV enabled share