Hi, I'm afraid I'm not sure what's going on. I downloaded it again and it opened fine for me. What version of Unity are you using/any warning or error messages showing up in console when you open?
It's possible that you need to have Blender installed, as I imported the .blend files directly instead of exporting to .fbx. If it's worth the trouble, you can download Blender here: https://www.blender.org/ and then try reopening the project.