Instead of searching for a single .rar file that might be outdated, most users use the "JSON Pack." When placed in your Fightcade folder, these scripts automatically download the correct ROM whenever you join a game lobby.
If you are looking for the file, it typically refers to a JSON configuration pack used for Fightcade 2 to automate ROM downloads. How to Get the Auto-Downloader
Locate your Fightcade 2 installation folder (usually in Documents or where you installed the emulator). Open the emulator folder.
Extract the contents of the downloaded .zip or .rar file into this emulator directory.