Seems I was correct. In order to use test cards and have the test URL supplied to your verification event, you must create a sandbox account in App Store Connect and then sign in to iCloud with that account on your device.

Figured out my problem. Seems supports3DS is required in the merchantCapabilities.

Any feedback regarding this error? I am experiencing the same thing when utilizing the Payment Request API.

Ok, ok, I got it. I had to put my retry in a loop and throw an await on my server call. Got things figured out from a writeup at mozilla.org. Lawdy, I thought Microsoft's docs were bad but after my Apple Pay endeavor, Apple's docs make Msft's seem complete and concise. @aprotyas thanks for pointing me in the correct direction.