RAR archive of 1.55 MB for Apple logic board 820-00244. Apart from the board number, the name says nothing about the contents, which could be a schematic, a boardview or a firmware image. Apple uses the 820 prefix for its printed circuit board part numbers, and the matching number is printed on the logic board itself. After extracting, check what the file type actually is. Schematics open in a PDF reader, while boardviews need OpenBoardView or FlexBV.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)