The official Steam Workshop—which provides thousands of community-made items—is only available for the official version. If you'd like, I can: Tell you how to install mods through the Steam Workshop. Check for the latest patch notes for version 1.27+.
Your safest option is to purchase the game on . However, Steam automatically updates to the latest version. To get 1.26 specifically, you have two legitimate options: Download People Playground 1.26 For Windows