CS2, as far as I know, is not usable for free by anyone, only those whom actually possesed a license of it before, it just is not clear and poorly executed(as anyone can go ahead and download them from their website with nothing preventing them), but actually it is not legal to do so If I remember correctly.
Indeed, it isn't legal. Also, Adobe changed the way you access those downloads. You need to make an account now, with a lot of personal information required.
The downloads are just for those who own a licence.