It's part of a Gwent promo that's sort of described in the first link.
To get it, first go to
Gwentand add the free card game to your library.
Then go to
Welcome Bonusand claim the bonus. It will display a "Get it Free" link to the Witcher Enhanced Edition, and when you follow it, the price for Witcher will change to $0.
Yep, I see your reply now, look like you're good