Archive named rtso-9002u, a 7z file of 2.56 MB with no brand, board or document type stated, so its contents cannot be confirmed from the name alone. Open it with 7-Zip or a compatible tool and inspect the files before use. If it contains firmware, verify the target chip and board revision match and save a copy of the original flash before programming anything. If it holds a schematic or boardview, compare the board number printed on the PCB with the one in the documents first.
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 @boardsscanrepo. Enginerys does not host this file.
How to open a .7z file
High-ratio compressed archive, often used for large BIOS collections.
7-ZipWinRARKeka (macOS)