I do get it, but I can't let an appx coming from nowhere. And you are missing the dependencies, recheck your wireshark logs
It is hosted where it's hosted to, how to say that, avoid problems. Bit slower, but works.
The project is not ours, but definitly Microsoft's, and modding the appx is not the best idea unless you want problems. Bugging the authentification can be made in different ways, be it through repacking and distributing unsigned installer, through a mini server, host file and others. Modding the appx you can even enable the debug mode, making the internal http server start allowing for content addition
Then you will need to find out how the licensing works, because of the missing content.
I think for clear reasons, we should continue this discussion in pm