RAR archive named PHONEBOARD, 26.4 MB, with no model or brand stated, so the contents must be checked after extraction. The name and size are consistent with a phone boardview viewer package, and another archive marks a v1.6.0 release of that kind. Tools of this type let technicians display board layouts, locate components and follow nets across layers. Extract with WinRAR or 7-Zip, scan the files with antivirus software before running any executable, and compare with the versioned package to see which build you have.
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 @uzb4422. 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.