GAMERIPPER tries to detect the encryption key automatically and decrypts. It should report an error if key not found, try running with the "-v" flag, that will create a log file with verbose messages, including the autodetected key.
Godot uses a military grade AES-256-CFB encryption, which in itself is impossible to crack. However the Godot executable usually stores the encryption key in plain text, so GAMERIPPER looks into the EXE file, locates the data segment looks for the key there. If the game has a modified Godot executable, which encrypts the encryption key itself or does not use AES for assets, then GAMERIPPER won't be able to rip the assets.
In the first case (encrypted encryption key) you can try
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which is a DLL that injects code while the Godot game is running and prints out the key or
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which is a GUI tool that brute force scans for the key (they both print out it as "Secret Key"). Then you can run GAMERIPPER, press F2 and specify that key manually and decryption will work afterwards.
In the second case (not AES method) there's not much you can do currently.