I have a VXDIAG VCX NANO GM with Tech2win. I use it for Vauxhalls. Great bit of kit.
That’s what i used and its fine on the later GM cars.
It better runs on Windows 7, and the VM is included on the little CD that came with it.
Download and install the latest VXMANAGER to the VM.
Do not change the timezone, and Do not attempt to update Windows.
Its all been turned off anyway. The VCX has to run on Chinese time. If you set the clock to GMT London, it will never work.
Plug in the VCX, open the VCXmanager.
Update its firmware. Click the License button to get the licenses applied to the unit.
Now its ready.
Now you can use TECH2WIN.
Or, additionally, you will need to acquire GlobalTIS to connect the car with GM to pull codes. And update all software within the car etc.
I’ve just checked, my VM is 26GB. That’s fully running with GlobalTIS all active.
I’ve also used it on a Saab once, and it was a later Diesel. 2010 i think and it worked fine.