ERROR: 10002 Authentication/Authorization Failed. You do not have permission to make this API call.
When attempting to complete a card-based Direct Payment checkout using PayPal Payments Pro, this error happens if your PayPal account has not been set up for PayPal Payments Pro, or if it has not granted our system permission to use that checkout method.
If you have enrolled for PayPal Payments Pro (an extra-cost upgrade with PayPal), please double-check every step of our PayPal Payments Pro integration procedure to make sure you haven't missed a step or overlooked anything—pay particular attention to everything under Step D: Setup API Access—and make sure the PayPal Email setting in your E-junkie Dashboard under Manage Seller Account > Edit Profile setting matches the email address you use to log into the PayPal account you have enrolled for PayPal Payments Pro.
If you are only using PayPal Payments Standard with a regular PayPal personal, Business, or Premier account—i.e., if you have not upgraded to the PayPal Payments Pro service at PayPal's end—then in your E-junkie Dashboard go to Manage Seller Account > Edit Profile > More Payment Options, then under the Accept Credit Cards section select I will accept Credit Cards via PayPal Standard, then click Submit to apply changes. To have the PayPal checkout site offer a card-based payment option for buyers who don't have a PayPal account, see this help page for tips.
Other services you could use to offer buyers a checkout option for card-based direct payment are covered under the Card Payment Gateways section on this help page.