I think it's a weird hybrid where you only need GameMaker's framework stuff to run it. When you look at the size the file when it tries to run its installer it should be around 18 mb. However we already had GameMaker installed on our computers so I don't know for sure. I would've uploaded a zip but it was past submission time so I was worried we'd break the rules. However, now that voting is over, we're trying to upload a zip version too.