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

Okay, so, I need to settle my doctor's statement. I went the website and it says I need a account number. Unfortunately, I am missing that! What am I supposed to check? Is there a way to find my client ID? Help me figure this out. It's really frustrating having to halt payment because of this. Veradigm and Pay My Doctor: How to Use It Navigating