When using NIOS Identity Mapping, you need Kerberos auditing logs to be enabled on the domain controllers to get event_id 4624, event_id 4634 plus others.
event_id: 4624 identifies the user, IP address, first seen and last seen
First of all, check your auditing settings:
Group Policy Management Editor → Computer Configuration → Policies → Windows Settings → Security Settings → Local Policies → Audit Policy. Set the following audit policies: Group Policy Management Editor → Computer Configuration → Policies → Windows Settings → Security Settings → Advanced Audit Policy Configuration → Audit Policies. Set the following audit policies: