OK sorry. I re-read and saw that you have a ChromeBook... my answer may not help.

I use the USB connection with GarageBand on my Mac. The Code has to be switched on to be recognized. It connects through MIDI.

I add a new track in GarageBand and use Microphone/Line as the input. I may have initially selected CODE as input and output device. I don't remember. It now defaults to it automatically.

You can also choose if you want to hear your guitar through CODE or not as you record.

Anything you play on another track in GarageBand as you record can be audible through the code if you like. It is NOT recorded again. The USB input only records your guitar.