Recently I had issues with configuring CardDAV-Sync and CalDAV-Sync along with Owncloud after a fresh Android installation. Specifying the well-known URLs just produced several error messages inside the app:
In the logs I saw a lot of messages about missing sub folders. After searching on the internet, I had a deeper look at the Owncloud web interface and spotted that the URLs have changed.
The following URL schemas worked for me:
The folder name contacts needs to be replaced by the name of your addressbook.