Small 60.5 KB RAR archive named ze600kl, a code that corresponds to the ASUS ZenFone ZE600KL model naming, though the name gives no indication of the actual contents such as schematic, boardview or firmware. Its size suggests a boardview or a compact document rather than a full firmware package. Extract it to see what is inside, then verify that your phone mainboard revision matches before using any layout or data for locating components, test points or tracing faults.
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 @cyberlanelectonik. 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.