Wallet order examples can not be added to wallet

At the moment I'm still studying the documentation on wallet order. See the following link: https://developer.apple.com/documentation/walletorders/example_order_packages, there are already finished .order files, but they cannot be added on my current IPhone 15 with IOS version 17.3.1. I get the error message via the Safari browser: Order cannot be tracked in Wallet This order cannot be tracked because the format is not supported.

Download via Google Chrome and open file via Wallet app shows the same issue...

Any clues as to why this might be and how to handle this situation?