Looping on Payment Confirmation page

Our website can’t receive an order. Because everytime someone do an order and click on “proceed to Checkout” button, they will stuck in between “payment page” and “payment confirmation page”. So they can’t enter “order detail page”. Please help, it’s just happening this morning till now. This is my website https://pef.unpad.ac.id/tiket-2/

https://www.ads-software.com/plugins/tickera-event-ticketing-system/