Step 4

Select Add New Mapping and create new mapping that maps immutableId attribute to externalId.
Select Ok to save the attribute mapping.
Select Save to commit changes, and go back to the previous screen.
Under Settings, the Scope field defines which users and groups are synchronized. Select Sync only assigned users and groups to only sync users and groups assigned in the Users and groups tab.
Once your configuration is complete, set the Provisioning Status to On.
Select Save to start the Azure AD provisioning service.

Select Add New Mapping and create new mapping that maps immutableId attribute to externalId.
Select Ok to save the attribute mapping.
Select Save to commit changes, and go back to the previous screen.
Under Settings, the Scope field defines which users and groups are synchronized. Select Sync only assigned users and groups to only sync users and groups assigned in the Users and groups tab.
Once your configuration is complete, set the Provisioning Status to On.
Select Save to start the Azure AD provisioning service.