RAR archive for the Quanta KW3 motherboard at revision A, about 994 KB, with no brand, model or full DA board number given. Matching should therefore be done by the KW3 code and revision on the PCB. Quanta, a large notebook ODM, prints these project codes on its boards. The contents are most probably a schematic for tracing rails, finding which component shorts a supply, reading pinouts and checking the power sequence. Inspect the archive to confirm whether it also includes a boardview file.
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 @IT_SERVICE_WORLD. 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.