How to get offer:
- Add GWENT Free to your GOG library (No need to download).
- Link your GOG account with GWENT by Logging in your GOG account here
- Subscribe here to claim The Witcher: Enhanced Edition and a GWENT Card Keg.
- The game will be available in GOG Galaxy or under your account library in GOG.
Edit 0: Updated post with GWENT Download size [4.7 GB]. (Credit to: JonShannow)
Edit 1: Just need to add GWENT to GOG Library, no need to download (Credit to: Selenium)
Edit 2: Added clarified instructions on where to find the game after claiming it. (Credit to: Agret)