Reference:
Basic certificate checking does not require an identity source. If you want binary comparison checking for the certificates, you must select an identity source. If you select Active Directory as an identity source, subject and common name and subject alternative name (all values) can be used to look up a user. https://www.cisco.com/c/en/us/td/docs/security/ise/1-3/admin_guide/b_ise_admin_guide_13/ b_ise_admin_guide_sample_chapter_01110.html

Explanation
https://www.cisco.com/c/en/us/td/docs/security/ise/2-4/admin_guide/b_ise_admin_guide_24/b_ise_admin_guide Step 1 Choose Administration > System > Deployment.
The Register button will be disabled initially. To enable this button, you must configure a Primary PAN.
Step 2
Check the check box next to the current node, and click Edit.
Step 3
Click Make Primary to configure your Primary PAN.
Step 4
Enter data on the General Settings tab.
Step 5
Click Save to save the node configuration.

Explanation
https://www.cisco.com/en/US/docs/security/ise/1.0/user_guide/ise10_man_id_stores.html