In order to save an audio track from the video file, you need to go to the section "Video Editor" and press the button "Export audio…"
The main window of "Export Audio…" has the following view.
When you have already chosen the suitable audio format, set its parameters and pressed the button "Export", you will get the result audio file. The function "Split files" – allows dividing the files into parts; every part will correspond to the separate video file, added to the converter.