Downloading a Spotify playlist for offline listening is a feature available to Spotify Premium users. Here are the steps to download a Spotify playlist:

1. Open Spotify and log into your Premium account.
2. Navigate to the playlist you want to download.
3. Toggle the "Download" switch to ON. The switch will turn green, indicating that the songs are downloading.
4. Once the songs are downloaded, you'll see a green arrow next to each song. This means you can listen to them without an internet connection.

Please note that this feature is only available for Premium users due to copyright and licensing agreements. Spotify Free users can listen to music only when they have an internet connection.