Authorize.net API for WooCommerce
3. Click New Transaction Key and then Submit
4. Get the code sent to the Account holder Email and press submit. Then Copy the two items (API Login ID & API Transaction Key)
5. Do the same thing for the New Signature Key (yes it will give you a new code by email) Then copy the API Signature Key which is going to be VERY long.
6. Then in Admin on your website, go to WooCommerce… Read more of this article