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

Okay, right, I need to settle my doctor's bill. I visited the website and it says I need a client ID. Unfortunately, I don't have that! What am I supposed to try? Is there a way to access website my client ID? Help me figure this out. It's really annoying having to stop payment because of this. Veradigm & Pay My Doctor: A Guide Navigating health