Haven't played EM4 for awhile now and I'm struggling to install this, I extracted it into the Mods subfolder, it appears in the game when I go to load it up (in game) it has a green spanner and when I load it up then start a freeplay game it is just the basic vanilla game.
Sorry if I'm missing something plainly obvious here
Is it an EM4 file or is it a normal file with all the game data in it? If its the EM4 file you need to install it with the mod installer like Stumpje said. Also which version did you download? The one from the link on the 1st page or from the downloads section?