If you select Credit Card it will pay using a profile you select from your profile group.
PayPal
If you choosePayPalas your payment method, you will receive a checkout webhook to finish the transaction. Please make sure your webhook is set up priorto the drop.
PayPal ACO
If you select PayPal ACO it will try to checkout using a random PayPal account that is logged in on the toolbox. If it fails to pay then it will send you a checkout webhook instead.