It doesn't matter if the drive is internal or external. What matters is that AD sees the share as an object and that you set up the domain controller to feed the users this share. It doesn’t just happen.
If you have the share setup right, you should go to a workstation and browse to the server with the share and see it. Once that works you can work on feeding the share as a mapped drive to your users.
All of this sounds like you need to read up on how AD works.
