RAR archive for the HP ProBook 450 G1, tagged L74 and 0108, probably a BIOS family code and version, though the name does not say so outright. At 3.74 MB it most likely holds a firmware image or update package; check the contents after extraction. Technicians use such files to recover a ProBook that stays dark or loops after a failed update, normally by writing the image to the SPI flash with a programmer. Back up the existing chip first, as it holds board-specific data such as serial number and product IDs.
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 @Satale_bios_esquemas_Laptop. 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.