To download an individual audio track:
Indicate the track you wish to download and isolate the track by selecting the headphones icon.
Click the Export button, located in the top right corner of the audio editor.
Indicate the audio format and audio quality and click Export file.
To download an individual track in the video editor:
To download a single audio or video track inside the video editor, hide or mute all other tracks except the one you want to download.
How to hide a track:
For video tracks: Indicate the track you want to hide, click on the video icon on the timeline, and then click on the eye icon.
For audio tracks: Indicate the track you want to mute, click on the audio icon, and then mute the track.
Then, follow the same export steps as above.
Trying to download an individual clip instead? Downloading clips and downloading tracks are slightly different. You can learn more about clips vs. tracks here.