First off, you will need to open the games files. You can do this manually through the File Explorer (It should be under \Steam\steamapps\common\Portal Stories VR), or by right clicking the game in your library, going to manage and selecting browse local files. You should see two files and an application called Lift.

If you see all of this, good job. Next up, select and right click on the Lift application and open properties. Go to the compatibility tab and under Compatibility mode choose Windows 7. Finally, apply and open Lift. If you followed along correctly then you should be able to play the game. FEEL ACCOMPLISHED!!!