Log in with a web browser on the following website with RZ account & password: xdav.oth-aw.de. Click on "current-user-principal" (right). Now you will see (under your name) the links to your address books (click on "addressbooks") and to your calendars (click on "calendars"). These paths will also work in programmes that do not support automatic configuration (e.g. Evolution). Calendars beginning with a "." (dot) are system calendars and are used in CalDAV for internal communication (appointments in/out, notifications, etc.).
However, please understand that we do not provide support for these accesses!