Hi M -
After you installed AD RMS, did you log out and log back in and then try to open the console? This is required to update the user's account to access the AD RMS cluster through the RMS MMC.
After installation the account used is added to the AD RMS Enterprise Administrators group on the local computer. To update the privileges of your account, you must log off and then log on again. Without this procedure, your
account will not have the required access rights to run AD RMS.