When syncing to your cloud storage, you have the option to download the tracks in a playlist to a second device.
As of MIXO v1.11, it is now possible to change the download location on desktop. You can do this via Settings/Advanced.
The default locations for downloaded tracks are as follows:
The path for iOS is hidden by the operating system
C:\Users\[YOUR USER]\Music\MIXO\Music (editable in Advanced)
Macintosh HD/Users/[YOUR USER]/Music/MIXO (editable in Advanced)
home/[YOUR USER]/music/MIXO/Music (editable in Advanced)