Unable to checkout

Hello,

I’ve been trying to set up the plugin at seasonsix.host. Whenever I try to buy something I get redirected to a 404 page when I click the checkout button.

You can try adding hosting and checking out here: https://seasonsix.host/order/?ccce=cart

It seems as though something is broken in the path when submitted it gets redirected here: https://seasonsix.host/cart?a=confproduct&i=0

The WHMCS Bridge installation shows nothing wrong.

The page I need help with: [log in to see the link]