RAR archive of 13.4 MB named ITX-6006UTC-6CD8, which looks like an ITX-format board identifier. The name does not say what the archive holds, so it may be BIOS files, drivers or documentation for that board. Open it with WinRAR or 7-Zip and check the contents before use. If it contains a firmware image, compare the model text silkscreened on the motherboard with the archive name. Also check that the image size equals the flash chip capacity, and read out the original chip with a programmer before writing anything.
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.