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

Okay, so, I need to settle my doctor's invoice. I visited the website and it says I need a client ID. But, I am missing that! What am I supposed to check? Is there a way to access my client ID? Can someone figure this out. It's really frustrating having to halt payment because of this. Using Veradigm & Pay My Doctor Navigating your medical costs