Obtain API Login ID, Transaction Key and Signature Key from client by having them login to their auth.net account 

Update Response URL and receipt URL in Authorize.net to proper setting  found in Account > Transaction Format Settings > Response / Receipt URLs

The URL Format for both should be: https://app.uxicommerce.com/authorizenet/(STORE_ID )

The store ID can be found in two spots:

  1. The URL for the dashboard - https://my.uxicommerce.com/store/17319100#dashboard -  In this example the store number is 17319100.  
  2. The bottom left hand corner of the UXiCommerce Dashboard