When configuring a GlobalProtect Portal, what is the purpose of specifying an Authentication Profile?

The additional options of Browser and Satellite enable you to specify the authentication profile to use for specific scenarios. Select Browser to specify the authentication profile to use to authenticate a user accessing the portal from a web browser with the intent of downloading the GlobalProtect agent (Windows and Mac). Select Satellite to specify the authentication profile to use to authenticate the satellite.

Reference https://www.paloaltonetworks.com/documentation/71/pan-os/web-interface-help/globalprotect/network-globalprotect-portals