There are few prerequisites which need to be set up in authorize.net(Merchant)before setting up LEXA.
1. Register with authorize.net and share the login id and transaction key details with LEXA to setup the payment processor.
2. Please make sure the authorize.net is in Live mode and not in sandbox mode.
3. Please make sure the Transaction API settings are enabled.
Steps for Enabling the API to enable the Transaction Details
1) Log on to the Merchant Interface at https://account.authorize.net .
2) Select Settings under Account in the main menu on the left.
3) Click the Transaction Details API link in the Security Settings section. The Transaction Details API screen opens.
4) If you have not already enabled the Transaction Details API, enter the answer to your Secret Question, then click Enable Transaction Details.
5) When you have successfully enabled the Transaction Details the Settings page displays.