The Spatial Tracking is built on Vuforia Engine's Ground Plane technology. It looks like the device you're using does not support Ground Plane (or else the operating system of your phone doesn't support it). Please see the list of supported devices and operating systems here: https://library.vuforia.com/articles/Solution/vuforia-fusion-supported-devices.html
I should add, this is for Spatial Tracking specifically. In Creo 4.0 M070, we reintroduced ThingMarks, which should work fine on your device.
Hmm that's very strange. Unfortunately, I'm not sure what's going on then. It should be working on those devices. Can you open a case with our Tech Support?
It shouldn't matter, no.
When you're using your iPhone, are you seeing the same error message as what you have in the picture you uploaded ("3D elements can be displayed because spatial tracking is not supported on this device")?
Also, are you using the latest version of Vuforia View?