Pass certificates and pass type ids play an important role on how Wallet works. Every pass needs to have a pass type id and needs to be protected by a digital signature created using a corresponding pass certificate. In order to be able to register a pass type id, you will need to be a member of the iOS Developer Program. Apple acts as a registry for Wallet to ensure proper use of the system, the very same was as a company register ensure that companies obey the law. During sign up for the iOS Developer Program you will need to verify your (business) identity and provide other necessary details. Once you are member of the Apple Developer Program you can register your own pass type ids.
Being part of the Apple Developer Program comes with some obligation in regard to use of your pass type id. Those obligations are part of the Apple Developer Program License Agreement and you should consult your Agreement for further details. One important obligation we would like to mentions is the requirement to provide your name, address and the contact information (telephone; email address) to which any end-user questions, complaints, or claims can be directed. Failure to comply with those obligations can in worst case mean that your pass type id will be revoked by Apple.