You'll get the unlocking key for the specific game launcher where that game is being launched from (like the origin, battlenet, EPIC ones etc.)

I bought RocketLeague, at a sale price with 2 DLC packs included. The payment was taken from my account, and unfortunately the code they provided to "activate" on Steam did not work. I contacted support. They responded quickly, but were asking for identity verification. I haven't given them any other name or any reason to need to verify identity. Most websites will accept credit cards or not, without requiring some second step. They asked for a picture of my ID. I saw no reason to do this and asked for a refund. I was not issued a refund at all. SIMPLY PUT, this is a scam. They are trying to steal not just your money, but other details of your identity. DO NOT USE THIS WEBSITE or APP

They just give you the key, you go to the game platform (Steam, Origin, Uplay etc.) and put the code in there to activate the game.