There are two ways to play a playlist on one or more screens.
Broadcasting from a playlist
From your playlist, click on the "Target Screens" tab.
Depending on your needs, click on "Add a screen" or "Add a group of screens":
Add the screen(s) on which you want to play the playlist. Once added the playlist will play on the screens automatically.
Broadcasting from a screen or a group of screens
From the settings of your screen or group of screens, click on the "Playlists" tab:
Click on Add a playlist :
Add the playlist(s) you want to play on the screen or group of screens:
Click on Add.