[AlphaCommerceHub] How to enable the «RefundPayment» process flow?

You should enable the FirstDataAU API:

[AlphaCommerceHub] How to fix the «Prior to activating a product all required field definitions must be complete» issue for the FirstDataAU API?

I have got an answer from the AlphaCommerceHub support:

I’ve updated the refund process flow to work for RefundPayment.