I got a reply:
Please note that if you do not know your PASSID number, we are working on an IT solution to allow you to link your account through your GOES User ID or other information. Please allow 1-2 business days for this to be implemented and deployed. You do not need to access your account unless you are already a member with pending travel plans. You do not need conditional approval letters for interviews. If you go to your interview, the officer interviewing you can provide you your PASSID.