You may have figured this out since – but is this on iOS or desktop? And are you getting the steady lights around the I1 knob, or do they keep flashing up and down the bridge? (If the latter, it indicates a connection problem; if the former, you should at least to be able to get sound from the iOS app, though the desktop app doesn't have built-in sounds and you'll need to connect to GB manually in the Audio/MIDI preferences.)
Yes, the Mac & PC desktop editors don't include built-in sounds; they're just for adjusting playing parameters. But you should be able to play the sounds in GarageBand; just connect the I1 and turn it on, go into Preferences => Audio/MIDI settings, and make sure Instrument 1 is selected as your MIDI input device (and that you have a sound or plug-in selected in GB for the I1 to control).
Enjoy! This is the beginning of an incredible journey…
Wilson Blount, III
Just received my instrument 1 today, downloaded the app/software from the site. I get no sound to work, strum, drums, nothing. Same result with garage band. Is there I issue going on? All firmware is updated btw