Open Unity and create a new proyect
Make sure you have a 3D template
Now close Unity and copy the ProjectSettings folder from the workshop folder to your Unity project folder:
Now we need to import the human workshop package into Unity:
The default location is:
C:\Program Files (x86)\Steam\steamapps\common\Human Fall Flat\WorkshopPackage
And replaces the files
Finally open Unity and go to prefabs folder and re-import all to fix the thumbnails:
