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

Okay, right, I need to pay my doctor's invoice. I logged in the website and it says I need a account number. However, I can't that! What am I supposed to do? Is there a way to find my client ID? Please figure this out. It's really annoying having to halt payment because of this. Veradigm & Pay My Doctor: A Guide Navigating your medical costs can