How to sync carnet with ecloud?

I downloaded the carnet app to my Fairphone 3+ and I also enabled it in my ecloud, but don’t know how to sync them. It offers only nextcloud as an option. Is it possible that its not possible to sync them and I can use them only separately?
Thanks for any help!

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

I had enabled ecloud synching already, and then Carnet just offered me to sync with that account when I installed. Seems to work okay.

I guess me too. but still no luck…