Why is my Shopify CC payment app not showing the 3ds simulator?

[Nermeen]

I'm following the Shopify doc. for creating the Shopify credit card payment app. I downloaded and ran Remix template, and it runs using the provided tunnels, but when try 3ds follow it, it refuses to show the 3ds simulator and load the URL inside the iframe.

Also, is there any other template like PHP?