ZIP archive for the ASUS S400CA notebook motherboard, revision 2.1, about 127 KB compressed. The name does not say what is inside. At this small size it more plausibly contains a boardview or a BIOS dump than a full schematic set. A boardview opens in viewers such as OpenBoardView or FlexBV to locate parts and test points. A dump is written to the SPI flash with a programmer such as a CH341A after backing up the original. Confirm the PCB shows revision 2.1 before relying on it.
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 @ITHINKHS. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip