To use an AD with filemaker, you need to do this:
- link your server machine to the AD by linking it to the domain in the system properties
- enable the external authentication in the FM server admin console
- create FM external accounts (in the FM file) using the corresponding AD groups name and assign a privilege set to this group.
Let say you have a group FM_Admin in your AD, and an external account with the same name in your filemaker file, all the AD users in that group will be able to open your FM file using their AD username and password.