I tried this approach as well, while only enabling calendars and setting the paths as you described. Unfortunately, that also failed with “Could not create account. Check sign-in details and try again. Authentication failed for URL: https://SERVER//SUBDIRECTORY/remote.php/dav/ocs/v2.php/cloud/user”. On the server, I get this in the log:
default nnn.nnn.nnn.nnn - - [18/Mar/2021:22:17:35 +0100] "GET /SUBDIRECTORY/remote.php/dav/ocs/v2.php/cloud/user HTTP/1.1" 404 0 "" "Mozilla/5.0"
Normally, the ocs
directory is at the root of SUBDIRECTORY - are you using any rewrites with regard to ocs
?