RAR archive of about 381 KB named LX67-MB-F, with no brand or document type given. MB most likely stands for motherboard, but the name does not reveal the manufacturer, model or what the archive contains. Extract it and check whether it holds a schematic, boardview or firmware image. For a diagram, compare the board marking with the title block before tracing rails or locating parts. For a BIOS dump, back up the original chip first and make sure the image size matches the flash capacity.
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 @cyberlanelectonik. 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.