Ngrok proxy for local development not working

Hello, I'm trying to make changes to my website's apple pay flow and an unable to verify if the flow works because I get the following error in the console when trying to pay:

TypeError: undefined is not an object (evaluating 'applePaySession.completeMerchantValidation')

By following this error message, I try to setup an ngrok proxy to verify my local development domain and that fails as well even though as you can see, the file does actually exist.

Can anyone help with A) giving me a different way to develop locally aka having a "successful" apple pay payment so I can verify my website's flow after payment or B) help me figure out why the domain verification is failing. Thanks!

Here is proof the file apple is looking for does exist

Ngrok proxy for local development not working
 
 
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