I actually downloaded and opened the ZIP file, found out why it wasn't working. first of all, this isn't in the vehicles\name format, the game can't read it. 2nd of all, this doesn't have a DAE file, so no vehicle mesh is given 3rd and last, what the hell is an i3d and shapes file? pretty weird, I'll put it in the mods folder and check if it's even functional.
100% --- Post updated --- Tried it, the mod doesn't work. there's a mod desc xml but no description shows up in the mod manager when I select it. no tractor in game either.
Its just one tractor stolen from the farming pack, just download the farmingpack on the official beamng website
just like coolcarguy said this is how you get it to appear: https://www.beamng.com/threads/farming-pack.29159/