Why can't customers add two items to their cart at checkout?

I’ve had several customers tell me they are having issues placing 2 items into their cart when checking out. There’s no issues with doing 1 item. When clicking checkout, it doesn’t do anything.

www.triggeredofficial.com

Password below:

Ka$ady11

Can you try adding character #90 with a quantity of 2 and try to check out?

I don’t see the images attached.