Hi,
He is trying to log into KMC using the Admin Console credentials. That is clear from looking at the URL in the address bar in the screenshot you attached [says partner_id=-2, that's the admin console partner].
He should go to Admin Console->Publishers, create a new partner and then use that partner's email and passwd to login.
He can also go to his partner's row under Admin Console->publishers and click on 'Manage' from the 'Actions' select box.