Fortinac Dynamic VLAN

You can start with this article to get an overall idea on how FNAC integrates with the network: Technical Tip: Comprehensive guide for a simple FortiNAC deployment
You can also take a look at this solution (based on MAC auth.): Technical Tip: A simple deployment including FortiGate/FortiAP (self-registered guest)
and also this guide: Machine Authentication

You can refer to this setting.