I wanted ro report a Problem with adding an account which is hosted on my own Baikal server. This may be just a server issue, but I suggest you may update the documentation if you find it appropriate.
Officially the Base-URL stated in your FAQ is /dav.php/ (e.g. https://server.example/baikal/dav.php/)(https://www.davdroid.com/tested-with/baikal/)
It only finds my account however when I type the principal URL https://dav.pascalpieper.de/dav.php/principals/NAME/.
When looking at the error log, it actually finds the principals path even when leaving out the /dav.php/-part, but somehow reports an internal server error upon request of that site. If I type directly the principal-URL, it finds the services of my user and succeeds.
DavDroid Error log: https://paste.fedoraproject.org/paste/OWimfyX2IAqbVcfdoj0P~Q
Webserver log: https://paste.fedoraproject.org/paste/SJTfzTIz1jHzU4gGPA7img
PS.: DavDroid is a great app and I enjoy using it otherwise.