https://www.cisco.com/en/US/docs/security/ise/1.0/user_guide/ise10_man_network_devices.html

In a Cisco ISE guest access deployment, several components must be configured to provide a complete guest experience. In this scenario, many of the necessary configurations have already been completed (such as network device settings, SMTP server configuration, and redirection via the authorization profile). However, to fully enable guest access via a Cisco Wireless LAN Controller with a guest portal, two additional components must be created:
Self-Registered Guest Portal:

Since the configuration already includes settings for sending credentials by email and redirection to a guest portal, the environment is set up for self-service guest registration. The self-registered guest portal is the web interface where guests can register themselves to obtain access. Without this portal, guests would not have a method to register and receive their credentials.
Guest Type:

Cisco ISE uses guest types to categorize and manage different kinds of guest accounts (such as contractors, visitors, etc.). Creating a guest type is essential because it defines the attributes and policies that apply to the guest sessions. This classification helps enforce the proper access controls and facilitates reporting.