Free as in “free beer”. You don’t own the rights to the beer, you don’t have the ingredient list, but it costs no money
But beer's recipe is open source, anyone can brew their own. It's a really bad analogy, it should be free Coca-Cola or something.
Or, since it seems to need explaining, the point is that "beer" is not one thing with one recipe and if somebody offers you "free beer" it is pretty obviously a specific kind and batch of beer.
It's free, but you can't do anything you want with it. Really it's free to drink on my terms - and that's certainly "free", but it's not "freedom" (as in free speech).