MSI MS-6749 service archive in ZIP format, 2.66 MB in size. The file name carries no indication of revision, document type or firmware version, so open it to see what it actually contains. For a schematic, a PDF viewer is enough to follow voltage rails, check where a short might sit and find test points. For a BIOS image, a hardware programmer is the usual tool, after first reading and saving the original chip. Always verify the MS-6749 code and revision on the physical board.
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 .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip