DAVx⁵ has been successfully tested with OwnCube.

On OwnCube you can store your files, directories, contacts, photo galleries, calendars and much more. Access your account worldwide from your mobile device, your desktop or any web browser. It's based on ownCloud.

DAVx⁵ settings

Base URL: https://your_server.owncube.com/

Contact group method: groups are per-contact categories