You don't have to download any of the apps on your phone. You just need to purchase it on the amazon website.
Updated the first post. I'm not sure when it ends.
wow im really surprised this worked, abusing the fuck out of it. if anyone has any other games that gives coins or wants to make a list please do im searching amazon like crazy atm looking for any more math bugs
AFAIK the rest of the promotion is still going, so you can still get $23 in credit (the free apps give you more than enough to buy GTA)they took the demo down
i missed my chance