According to the Authorize.net knowledge base:
How do I resolve the following error: "This account has not been given the permissions required for this request"?
This error indicates that a Login ID is being used to connect a website or billing software to the payment gateway. For example, if an Account Owner, Account Administrator, Transaction Manager, or Account Analyst login ID is used for website or software implementation, this error will occur.
To resolve this issue, the API Login ID and Transaction Key will need to be implemented to properly connect the website or software to Authorize.Net. The API Login ID can be obtained by following these steps:
1) Log into the Merchant Interface at https://account.authorize.net.
2) Click Settings in the main left side menu.
3) Click API Login and Transaction Key.
If an API Login ID needs to be configured, this page is where the option exists. If an API login ID has already been configured, it will be visible here."