A 4.50 MB RAR archive that, from its name, contains a BoardViewer program credited to Rito rather than a board-specific layout. Boardview viewers open PCB layout files so a technician can search for components by designator, see which nets they connect to and find test points on both sides of the board. The name lists no supported formats or version, so check what is inside after extracting, and scan unknown executables before running them on a bench PC.
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 @esquemaseletricos. 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.
7-ZipWinRARThe Unarchiver (macOS)