PayPal Example missing /pay page?

Perhaps it is me but there is no pay.html page, the demo just goes to a 404

https://github.com/firebase/functions-samples/tree/master/paypal

Inspect the paypal example at the repository path in the issue and reproduce the demo flow that leads to /pay. Check how that route is expected to be served and verify whether the missing page or route causes the 404; done means the PayPal demo no longer reaches a missing /pay page.

Written by the indexing model from the issue text.