webDAV: sync users access with AD

have to share a directory for a DMS system via webDAV.

1st I created a samba share to mount the dir from the dms clients (win, mac) incl. the auth.
On the UCS samba server I add in the apache2.conf (could also new cfg in …/config-enable/availible)

Alias /webdav /DMSshares/DMSsync
<Directory /DMS_shares/DMSsync>
DAV on
Options +Indexes
AuthType Basic
AuthName “Anmeldung zum WebDAV Verzeichnis”
AuthUserFile “/etc/apache2/user.passwd”
Require valid-user
ForceType text/plain

2nd created some users via htpasswd which could connected to the DMS system.
These users can connect to the DMS system - no problem.

Question: how can I sync these users with the users of the AD & the samba server ?