Authorize.net is not literally a payments processor.  Its a gateway (pipe) that connects a shopping cart, such as the one in MeetMax, with your processor.   Processors are services like Paymentech, and process the transactions they receive via the gateway, retrieve the money from the customer using the Visa network, or Mastercard, Amex etc - and deposit the funds in your bank.

If you do not have a processor, you cannot use Authorize.net - you will need to use Stripe or Paypal Pro.     To get a processor - you go through your bank to get an online merchant account - and your bank will set you up with the processor - and the processor will set you up with the gateway (which will be either Authorize.net or Payflow Gateway).

Once you have an authorize.net account - setting up to work with MeetMax is easy.  You just send us the API credentials, and we make the connection.

Log into Authorize.net - go to Account

From there go to API Credentials and Keys.

If you have never generated an API set - do it - and send the generated API login ID and Transaction Key to your MeetMax support rep.  They will make the connection and you will be ready to take payments.   Note - Authorize.net only allows you to generate one set of API credentials - if you work with more than one shopping cart service, you will have to use the same API set for each.