Hi Marcus.
It would be nice to have some idea going in for what the requirements are. - I have to admit, I don't understand why I can't preview the 3D experiences right on my computer. - Likewise, when I try the QR code on my iPhone 6 ... well, I'm hardly surprised to not see anything in 3D, but it wouldn't hurt to have a little more detail than "Scan this QR code on your iPhone or iPad."
I suppose I could mention that I've done some game development and a little bit of VR/AR, but have never heard of the USDZ file format before.