Active: Activate the payment gateway/Disable the payment gateway .
Test Mode: Decide on whether you'd like to test the gateway out (This means all transactions made within the store will only be considered a test transaction).
API Login ID: Input your Authorize.net API login ID.
Transaction Key: Input your Authorize.net Transaction key.
Developer Mode: Decide whether the gateway will be in developer mode. (If set to "Yes", transactions will only be considered test transactions)
Live Endpoint: The URL left within this field by default is the correct endpoint, but can be changed to any emulated API endpoints as well.
Developer Endpoint: For Development, this (by default) is best utilized in the test environment, for developmental purposes. The default API endpoint can be changed to point towards an emulated endpoint at anytime.