An administrator has an active directory (AD) server integrated with FortiAuthenticator.

To allow members of only specific AD groups to participate in FSSO with their corporate FortiGate firewalls, the administrator can configure SSO groups and assign them to FortiGate groups. SSO groups are groups of users or devices that are defined on FortiAuthenticator based on various criteria, such as user group membership, source IP address, MAC address, or device type. FortiGate groups are groups of users or devices that are defined on FortiGate based on various criteria, such as user group membership, firewall policy, or authentication method. By mapping SSO groups to FortiGate groups, the administrator can control which users or devices can access the network resources protected by FortiGate.

References: https://docs.fortinet.com/document/fortiauthenticator/6.4.0/administration-guide/906179/single-sign-on#sso-groups