Allowing people in "Domain Users" group to log in through AD integration

I AM NEW TO THIS AND HAVE NO IDEA HOW TO RETRIEVE LOGS ETC

Expected behaviour

The system should allow ANY user to login who has an account on Microsoft Active Directory.

Actual behaviour

Only people that are administrators can log in through AD to OwnCloud

Server configuration

Operating system:
Univention appliance on VMWare ESXi.

So I guess you have set up your Univention appliance to join an existing Microsoft domain, correct?
Have you’ve had a look at the existing documentation?
https://doc.owncloud.org/server/admin_manual/appliance/configuration/add-groups-and-users.html