The game frequently goes on sale. You can add it to your Steam Wishlist to be notified of price drops. Why Avoid "Free Download" Sites?
Check the Darkest Dungeon II Steam page during events like Steam Next Fest, where a free demo is sometimes offered for players to try before buying.
The version you mentioned (v0.16.39101) is from an old Early Access build. The current version includes major updates like the Kingdoms game mode and refined character paths that are missing from older, pirated versions.
Sites offering free "full versions" are a common source of viruses and ransomware that can compromise your PC.