[Help] Exporting fbx file to Steam Workshop as a .unity3d (Vehicle)

Hello UnityNinja community, I am currently in need of help with some complicated exporting project.. I am a high school student in Japan, and we had a 3D modeling project where I made a simple cadillac in Blender.


My ultimate goal is exporting this vehicle in to a free survival game called "Unturned," driving your favorite car in a game, cute dream aint it?

There are a couple of documentations created by the game programer, but sadly I am still new to modeling and is a bit too complicated for me..
http://steamcommunity.com/sharedfiles/filedetails/?id=470771210&searchtext=workshop+objects
http://steamcommunity.com/sharedfiles/filedetails/?id=470772671&searchtext=workshop+objects
Existing workshop vehicle made by someone else:
http://steamcommunity.com/sharedfiles/filedetails/?id=448740957&searchtext=

There's also an example unitypackage file made by the game programmer:
https://www.dropbox.com/s/0esrv8milbv0csk/Vehicle.unitypackage?dl=0

If anyone wants to give a helping hand to a kid's dream.. That will be fantastic!