Both sponsor and administrator account permissions are assigned using admin profiles. An admin profile is a set of permissions that defines what actions an administrator or a sponsor can perform on FortiAuthenticator. An admin profile can be assigned to an admin group or an individual admin user. A sponsor is a special type of admin user who can create and manage guest accounts on behalf of other users.

To enable guest portal services on FortiAuthenticator, you need to configure a portal policy that defines the conditions for presenting the guest portal to users and the authentication methods to use. You also need to configure at least one post-login service that defines what actions to take after a user logs in successfully, such as sending an email confirmation, assigning a VLAN, or creating a user account. Configuring a RADIUS client or an external authentication portal are optional steps that depend on your network setup and requirements. Reference: https://docs.fortinet.com/document/fortiauthenticator/6.4/administration-guide/372404/guest-management