Zip archive with an uninformative numeric name, roughly 485 KB, giving no hint of device, brand or board number. The small size fits a boardview, a compact schematic excerpt, a small firmware image or a utility. Extract it and inspect the contents before use, checking file extensions and any embedded model names. If it turns out to be firmware, confirm it matches your board and flash chip size and back up the original chip; if it is a boardview, open it in a viewer such as OpenBoardView and compare the board number.
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 @cidschematicandboardviewofficial. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.