Configuring an identity source with type "Active Directory over LDAPS" fails with an error message:
Cannot configure identity source due to 'Identity Store certificates' value should not be empty.
VMware vCenter Server with AD over LDAPS
This is an expected error as certificates are requisite for LDAPS to facilitate secure connection.
Steps to configuring AD over LDAPS are outlined in KB: Configuring a vCenter Single Sign-On Identity Source using LDAP with SSL (LDAPS)