Your selection might affect the way that the service provider (SP) looks up and associates your users at the SP site. You and the SP should decide in advance which option to use.

The choices of name-identifier types depend on whether you use the SAML or WS-Federation protocol. For more information, see one of the following.
Note:

The Identity Mapping window does not apply for connections using the WS-Federation protocol in conjunction with JSON web token (JWT)-based single sign-on (SSO) tokens. Instead, work with the SP to define an attribute contract that it can use to map users to accounts at the SP site.