ZIP archive for MSI board MS-9631 revision 1.0, 773 KB in size. Whether it holds a schematic, a boardview or another document is not stated in the name. A separate 0A revision of the same board exists, so check the revision on the PCB to avoid mismatched references. A technician uses such files to follow power rails from the input through the regulators and to identify components by reference designator. ZIP opens natively in Windows, and the documents inside usually need a PDF reader or a boardview program.
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.