The standard CardDAV and CalDAV connectors in Sailfish OS cannot handle Zimhra redirect from the path in documents (/dav/username@domain/Contacts and /dav/username@domain/Calendar) so we must punch in the real address instead.
My configuration is using email address as username so the @domain part is included always in the path so I am not 100% sure if we need incude @domain in path. Let's presume we don't :) Please comment if I am wrong.
The real path to Contacts CardDAV and CalDAV is
/service/dav/home/usename/Contacts/ /service/dav/home/usename/Calendar/
This is straightforward
And that's it!