RAR archive of roughly 481 KB for Apple board 820-2102, the name giving no schematic number, revision or board role. A related set for the same number is tagged LIO with schematic 051-7226, so this is probably the same I/O daughterboard, but confirm once extracted. Apple numbers PCBs as 820-xxxx, and the code on the board must match before you rely on pinouts or part references. Use the material to trace connector signals, port power and protection components.
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.