Some businesses require a different on-boarding procedure. They want clients to register in their system by themselves, accept all the terms and provide accurate data. That's why you can enable self registration of a client in a client panel:

When you do that clients can go to your client panel website and select Sign Up option

When people register in your system they will be asked to provide a personal data that will be used for your verification.

When you verify it and accept it you can assign cycles, billing and invoices to your clients