Windows 2008R2 server with AD role built.
User group: owncloudgrp
User in owncloudgrp: aaa, beta
Users must have logon name, first name, last name set.

Configure the owncloud:

Server:

User Filter:

Login Filter:

Group Filter:
Every time you change these two sections, wait for a few seconds until more than zero users discovered.

Advanced – Connection Settings:

Advanced – Directory Settings:

Expert:
Add internal username: sAMAccountName