According to the uploader “After thinking for a long time, I’ve decided to open the source files for the Antonov An-2. Since I don’t have time to continue the development, I’m giving this opportunitiy to the community to continue the development. Feel free to update this repo to keep developments in one place. This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.”
Check it out at their dedicated web page.