FRUSTRATED PAY MY DOCTOR: WHERE'S MY CLIENT ID?

Okay, therefore, I need to pay my doctor's invoice. I visited the website and it says I need a account number. Unfortunately, I am missing that! What am I supposed to do? Is there a way to find my client ID? Can someone figure this out. It's really frustrating having to pause payment because of this. Veradigm & Pay My Doctor: A Guide Navigating