We have many Arrays and I would love this script to

Can you post the error? You have to connect to the array first with new-pfaarray and use the object that is returned as input into subsequent SDK calls. So in your loop, connect to the array with new-pfaarray and send that return into a variable $objArray for example. Then use $objArray as input to the array parameter for New-pfanamedcertificatesigningrequest. For the sake of session management, you can add a disconnect before your next iteration of the loop.