By default, all users from the managed AD domains are assigned to the built-in security role called 'Domain Users'. This gives them the ability to login to Adaxes, search and browse AD. To grant more privileges to users, you need to assign them to other security roles, for example, Help Desk, Account Manager, etc.
For more details on security roles, please see the Delegating Permissions section of the Adaxes tutorials.
Additionally, you can customize the Web Interface to allow or deny specific users or groups to access the Web Interface resources.