https://github.com/ArduPilot/Schematics/blob/master/F4BY/F4BY_V2.1.5.pdf"Please go through the schematic in the attachments and revert with the KICAD Schematic in PDF Format." what does it mean.
More detail would be helpful. But with the information you gave, seems like they want to convert the eagle file into to kicad maybe?