Small 235 KB RAR archive with the repair guide for the ASUS P8Q67-M DO, a micro-ATX business board using the Intel Q67 chipset, likely the DO in the name refers to a specific variant. Given the size, expect a short document or a few pages covering the power sequence, key rail voltages and measurement points for diagnosing no-power or no-POST faults. Extract with 7-Zip or WinRAR, and check that the board revision on the PCB matches before trusting any readings.
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 @ZINFOSERVICECHANNEL1. 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.