In the current Airtime interface the view of the Library is transparent across folders. The folders are automatically organised by creator and album metadata, like this example:
Permissions are based on the user that uploaded the file, not where that file is located.
To show only the files uploaded by a certain user, use Advanced Search Options on the Owner field (see attached screenshot). You need to enable the Owner column for this search field to be visible.
If the issue is the requirement for user-based control over uploads, one way to accomplish that is to create a watched folder on the server for each DJ user - see http://en.flossmanuals.net/airtime-ru-2-3/-/
You would then create file server shares (local network) or SFTP accounts (remote network) for the different DJ and Program Manager users with the appropriate permissions.