If you're working with a multitrack Sequence and would like to export individual files for each track, you can do so in the Sequence Editor.
Edit the Sequence by right-clicking on your Sequence in the timeline and selecting "Edit sequence" (Cmd + Shift + O on MacOS, or Ctrl + Shift + O on Windows).
Mute all of the tracks, except for the one you would like to export, by pressing the M (Mute) button.
Exit the Sequence editor by clicking the X button at the top-right, then Export your Composition using the normal export workflow and you will have a single mono track for the un-muted track.
Repeat this process for all other tracks in your sequence, then you're done!