Archive named after the Intel 945GCCRL, a desktop board name pointing to the Intel 945GC chipset; the name does not say what the 454 KB RAR holds. Given the size, it most likely carries a BIOS image or related firmware rather than schematics, but open it and check the contents first. If it is a BIOS dump, it can be written to the board firmware chip with a programmer to fix a non-booting system. Confirm the board model on the PCB, back up the existing chip and match the image size to its capacity.
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.