DAVx⁵ has been successfully tested with Kolab Now.
Kolab Now is a fully featured secure collaboration and communication service that is easy to use on any device.
Choose "Login with email address" and enter your Kolab Now email address and password.
Contact group method: groups are separate VCards
See also: Android CardDAV & CalDAV setup (Kolab Now KB)
Last updated: 07 Feb 2020