The Fly-CDYv2 has been replaced by the Fly-CDYv3 https://github.com/Mellow-3D/Fly-CDYv3
RRF information can be found here https://teamgloomy.github.io/fly_cdyv2_general.html
Klipper information can be found here https://mellow.klipper.cn/#/board/fly_cdy_v3/ and here https://mellow-3d.github.io/fly-cdy_v3.html (although both instructions state they are for the CDYv3, the pinouts of both boards are exactly the same)
For Klipper support please join this Discord Channel https://discord.gg/zAung88zbK
For RRF support please join this Discord Channel https://discord.gg/uS97Qs7