RAR package, 1.53 MB, for Apple logic board 820-2807. Besides the number, the name gives no model, revision or content details; a second archive of identical size exists under a duplicate name, so it is probably the same material. Extract it to check for a schematic PDF or boardview file. After verifying the 820 number printed on the PCB, use the documents to trace power rails, follow enable signals and locate components and test points.
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 @Mac_Shematic_Santale. 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)