Packed RAR file for the M2N68-AM PLUS motherboard, roughly 254 KB. The name identifies only the board model, so whether it carries a boardview, schematic or other service data is not stated. Files of this size are typically repair documentation that lets a technician find parts, trace signals between the chipset and connectors, and measure voltages at test points when a board fails to power on. Extract it with any RAR-capable archiver and match the board revision printed near the slots or PCB edge before relying on the layout.
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 @boardview. 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.