A lot of people seem to be having a lot of difficulty with this. This download is a pack. The download clearly states that you must unpack/unzip this file.
You need to take the 3 mod files from within this download and place them in your mods folder.
Credits:
WMF Modding
tractors and truck have no wheels and I can’t enter into them. unzip the 3 mods to mods. And I can’t save the game.