ZIP package of 7.67 MB named after the B350AM4-M motherboard, a B350 chipset board for the AM4 socket as the name indicates. The contents are not described, so it may include a firmware image, schematic or other repair material. Extract it with a standard archiver and review each file. For BIOS recovery, read and save the existing SPI flash with a programmer before writing, and verify the image size equals the chip capacity. Check that the model and revision on the PCB match 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 @laptopchiplevelrepair. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.