Info
The payment is processed via direct debit to your bank account. You will in the online form, which requires the same information as filling in the manual I-765. Once you post the transaction to the system, you get your receipt number, and it tells you you need to call the National Customer Service Center to schedule an appointment for digital fingerprint, photo and signature collection with your local Application Support Center. As I said, I got an appointment there for tomorrow.
One interesting thing is that the online case does not yet reflect the new receipt number, so it suggests to me that the case status system is updated by some sort of batch process.