Windows executable named CHROMEBOOKUNLOCKER, about 9.9 MB, intended by its name as a Chromebook unlocking utility. The name gives no supported models, version or method, so its scope is unknown. Tools of this kind are typically used around Chromebook firmware or enrollment, which may require write-protect removal or a programmer. Run unknown executables only in an isolated environment, scan them with antivirus software, and keep a full backup of the device firmware before attempting any modification.
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 @lappysan. Enginerys does not host this file.