You can assign the music accessible to a sub-user from the Users tab:

Then choose "Assign" next to the user you would like to assign:

From the pop up window, you can choose which playlists, mixes or schedules are available to your users by clicking the check box on the far right. 

Clicking on the "Autoplay" button will make that selection play on a Soundmachine hardware player, or by logging into the web. You can choose the playback options for autoplay by choosing "Full, Mellow, or Upbeat" when setting the autoplay setting. 

You have the option to remove a playlist from a user account, by unchecking the right hand box.