HP EliteBook 840 G3 repair archive for board 6050A2822301-MB-A01, revision A01. Note that this number differs from the other 840 G3 board, 6050A2728501, so both variants exist. The 6050A pattern is Inventec's numbering. At 10.9 MB the RAR likely contains a schematic and possibly a boardview, useful for locating components, test points and power rails. Confirm which variant you have from the PCB label before using the data.
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 @hrtechno. 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)