Your colleague might have mislead you a little there. 🙂
It's on mobile platform where you can only shuffle tracks of your playlists/albums, except on a few playlists. I recommend checking out this article to learn more about Spotify free on mobile!
On desktop clients and web player, however, there is no shuffle limit. You can pick and play, create as many playlists as you want and listen to any artist in any order. Premium features are high quality streaming (free is ~160kbps ogg on desktop), ability to download playlists for in-app offline listening and more, which you can read about in this article. 🙂
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