Re: case studies using Fortiauthenticator
It would be the obvious primary use case.
However, there could be a situation where you want to provide centralized LDAP authentication without tying into Microsoft Active Directory. Fortiauthenticator will do that as well.
Plus it can provide centralized token administration across many Fortigate devices. If you just have one site, or location, best to skip it and go with an HA (High Availability) setup instead.
Multiple sites and Fortigate devices? It is much more attractive then.