Please refer to the How to obtain an eCommerce Merchant Facility for Authorize.Net if you do not already have your Authorize.net credentials.
In your Authorize.net account. Click on the Account Tab (1), then click on API Credentials & Keys
Note the username (1). This needs to be entered into Salesforce
Generate a new key (2).
Copy the generated key (1) and continue (2)
This becomes your password for within Salesforce
Once you receive your login details (API Login Id and Transaction Key), then you need to enter these into the Merchant Facility.
Navigate to the Merchant Facility Tab, press [GO] to see all facilities and click into the one you wish to use or press NEW button to create a new one.
On the Merchant Facility, make sure the following details are entered/updated
- Payment Gateway is set to "Authorize.Net"
- Payment Gateway userId is set to the API Login Id provided
- Payment Gateway Password is set to the Transaction Id provided
- Environment is set to Sandbox or Production
- Set the Credit Card Masking to "4X....4X"
In order to be able to do refunds, the Credit Card Masking needs to be set to "4X....4X"