A client is looking to pay invoices via ACH - I see that is possible but they are wanting to pay without having to fill out the information provided in the payment link

Hello,

If they want to pay via ACH, and THEY want to initiate the payment, then they will have to enter their banking info on the payment link.

If they are willing to provide you with their banking information, you can process the payment on your end by manually creating a receive payment and entering their banking info on the payment screen.  This will keep them from having to enter their information.