Spotify How to make "Play Button" play preview without user login

I am trying to find out what feature of Spotify API/services enables to play content preview without asking user to login in to Spotify. For example, site Billboard has pages that have Spotify player with song preview, and do not ask for user login (url: http://ift.tt/1Q2PJOw). I do not see any configuration options for Spotify "Play Button" to have such behavior (it asks user to login immediately). How could I achieve similar user experience (play song preview using Spotify without requiring user login)?

If that cannot be achieved on Spotify platform, is there another platform that allows to embed song (playlists) previews (or full versions) for users to anonymously listen?