RAR archive of 1.88 MB holding a PDF schematic for Quanta project X31, board DA0X31MBAF0, marked kbl-u, meaning an Intel Kaby Lake U platform, with a date code of 20160805. The name names no laptop brand, and the numbered suffix suggests a duplicate copy. Unpack it with any RAR-capable archiver such as 7-Zip or WinRAR. Quanta uses the DA0 prefix plus project code on its boards, so check that marking and the revision on the PCB before tracing rails, signals or parts.
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 @abgm_manutencao_esquemas. 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.