Merchant ID for client company

My company is a PSP and we have AP supported on our website. I am trying to enable AP on one of our clients domains and Apple Support told me that I all I needed to do was be added to the clients Apple dev team account as admin and to then create a new merchant ID under their account. I have done this, I created a AP payment processing certificate and a AP Merchant Identity Certificate, verified the domain and I still can't get it to work on their webiste. Any ideas?

Merchant ID for client company
 
 
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