: Drag the extracted files into the main game folder. If prompted to "Overwrite existing files," select Yes (this is usually required for mods/DLC to work).
: These are patch files for Ragnarok Online servers. File: COS_RO2_DLC.rar ...
Since .rar is a compressed archive, you will need software to open it. : Use 7-Zip (free and open source) or WinRAR . : Drag the extracted files into the main game folder