Follow the specific instructions provided by the modding tool you are using (such as the Groove Coaster Chart Editor ).
Use software like WinRAR or 7-Zip to extract the contents, as these handle the .rar format most reliably. How to Use the Extracted Content If the file contains custom songs for the Steam version: Groove.Coaster.rar
Locate your game’s installation folder (usually under SteamApps/common/Groove Coaster ). Follow the specific instructions provided by the modding