ok, first, be advised that baikal now doesn’t make use of the ‘flat’ package distinction anymore, just get the single latest release (0.3.5) from github.
Please not that you are discarding the baikal instructions if you don’t use the well-known urls.
However, with the latest package, you just point to the baikal/html/dav.php/ and you’re fine (it will autodiscover calendars and addressbooks).
For a previous release (tested 0.2.7), you use card.php or cal.php .
What is weird in your logs is the HTTP exception 405.
Baikal comes with a TROUBLESHOOTING.md have you tested the output of (alternative is --digest for digest, replace your usernames and password )
curl -so - --digest --user testuser:testuser http://server/baikal-flat/cal.php/principals/testuser? It should give you an XML document containing GET is only implemented on File objects.