In order to use a Realm Linux workstation with your Unity/EOS account, you must ensure that the authentication methods are set up properly. For the most part, this is taken care of in the %post section of a kickstart installation with the realmconfig tool. The main points are to ensure that both Hesiod and Kerberos are enabled and that the proper information is given to locate the Hesiod and Kerberos servers / services.