How to download a game?
First you need to find out who is the publisher of the game. After that you will have to use their download service in order to play the game.
Please note that the code that was provided to you from us, works via activating a product, not via purchasing a product. So please try the option to activate a product from the publishers download service.
EA ->www.origin.com
Ubisoft ->www.uplay.com
Steam ->www.steampowered.com
Blizzard ->www.battle.net
You will find instruction how to use the services from their home pages.