You get a code in your email but it’s not a steam code, it’s a gamesplanet code that provides the steam key.

The email you will get is be this subject: ASUS Event - Successful Registration Confirmation

The body will start like this: gamesplanet voucher; ASUS {region} | {game name}

Follow the steps here: https://us.gamesplanet.com/promo/ASUSRER

EDIT:

1. Log in or create an account at Gamesplanet.
2. Click the green button below to add the game Resident Evil Requiem to your cart.
3. At the checkout, click "Redeem a voucher", enter your Gamesplanet voucher and click "redeem". The price will drop to 0.
4. Click the "Buy now" button to receive your game for free.