You extract it in a seperate folder and run the .exe for all of the releases. The game won't run if its missing anything included in the .7z
Sounds like your system can't run it. It's settings are set to ultra and then some for that demo.
It's recommended your gpu is on the latest stable driver and you have a gpu that is around or above the performance of a 1070 for the medium settings. I recently redid a low and fisher price quality for those that fail that or on a aging laptop