How does paying by EBT work? Is it like a debit card that you enter into the store site during checkout, or is there a back-and-forth between the store website and another website?

Also, please don't be shy about using other browsers (on Windows 10, you have Microsoft Edge) when you run into a problem like this. Your food budget certainly comes before Firefox loyalty in my book!

The EBT registration includes a remote site popup by the DTA in order to securely enter your PIN. This window never appears. Chrome works fine. Why can't FF also work? It is a registration procedure, just like a credit card, it allows EBT for home delivery payments for food items. It is a one-time process, once completed successfully. (Also be advised the DTA in my state uses the STUPIDEST NUMPAD EVER: the numbers rearrange themselves after every input! that means the first row could be 123 or 693 or 859 or ANYTHING! dumbest idea I've ever seen. My fingers know my PIN, when you change the numpad you go outside of expected reality!) Thanks.

Could you try turning off the popup blocker and see whether that makes any difference: Pop-up blocker settings, exceptions and troubleshooting.