You need to have a Spotify Premium account to use Spotify Connect.
1. Open Spotify, start playing content.
2. Choose your Pantheone I speaker in Spotify among Available devices (found at bottom of played)
Go to Pantheone app to manage music and speakers.
About Spotify Connect »
To play Spotify Free with Pantheone I connected audio units, use Bluetooth and re stream audio to play to more speakers in a group.