I want to make a mod for a car from the game, but whenever I open a blender file from the car, a cube pops up. (I know, I'm new.)
I don't know which type of item it is. Is it a .obj file? Is it a .dae file? (It's the Autobello, that's all I'll say.)
If you want to import something else than a .blend file, then you need to do it through File -> Import (then select the .dae, .obj or whatever it is). Dragging & dropping works only for .blend files