This may be worth reading from the site you used :
Original Retail CD Key: This product might show ideal for gamers with the original CD/DVD of the game but there CD-KEY was banned, stolen etc. Please note that the publisher of the game might not support direct digital download of the game from its website / servers. The CD-Key provided by G2PLAY comes from original package of the game and you will be the first owner of this CD-Key and enables you to play on the official multiplayer servers of the game. Its supposed to be used if you "lost the retail key when you bought the game".
AFAIK, there is no CD key with the game, so I would assume this may be a bogus key, even if it isn't, from that paragraph I quoted, if you want to use the key, you need to buy a retail copy of the game.
Smells like fish spirit to me
