Archive of 906 KB labelled 558-1-4-01 with revision R21, packed in RAR format. The name is a bare part or board number without a manufacturer or device model, so the target hardware cannot be confirmed from it. Its size suggests a schematic or firmware package similar to the other numbered archives in this set. Extract it and identify the contents and board before use, and compare the number and revision printed on the PCB, since a mismatched document or dump will mislead diagnosis.
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 @schematicslaptop. 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.