Amazon Pay works with a popup in which the user logs into Amazon Pay and selects a payment method. A so called "Order reference ID" is created and the FundraisingBox need this ID to finalize the payment.
If you have activated
autoRenderErrors everything works automatically and you haven't to care about the Amazon Pay specials.
The Amazon Pay popup requires at least a selected amount and optionally the payment interval. So you have to collect this data before submitting the form.
If you have deactivated
autoSubmit you have to listen to the fundraisingBox:amazonPaySuccess Event.
If you have deactived
autoRenderErrors you have to listen to the fundraisingBox:fieldError Event.