An archive of repair files. Shared as “TP.MS338.PC821_ 4G_512G_ FHD_ EMMC_RT809H.rar” — a .rar file, 279 MB.
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 @tvsoftwareworld. 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.
7-ZipWinRARThe Unarchiver (macOS)