RAR archive of about 852 KB for the MSI MS-7546 motherboard, revision 0A. The token RIOS in the name is most likely a misspelling of BIOS, so the package probably holds a firmware image, but confirm that after extracting it. Before flashing, check the chip marking on the board so you know the flash size, because an image that does not match the chip capacity will not fit. Read and keep a copy of the original contents with your programmer, and make sure the PCB is really MS-7546 rev 0A, since MSI firmware is tied to the exact 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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.