Some features are disabled in mute-mode to make sure you will not accidently save, download or comment on a different jamtrack from the one you are currently hearing. You may either lift the mute-mode to download or interact with the currently displayed remix, or move to the currently playing track with the green GOTO button.
Managed to convert the download file using VLC. For some reason the mp3 when put straight into GarageBand plays corrupted.
Anyway, all fixed now and I am happy to join you Peter on this marvelous track.