Step 1. In the left panel, right-click a playlist you wish to open.
Step 2. Select 'Collaborative Playlist'.
Step 3. Right-click on the playlist again, then scroll down to 'Share'.
Step 4. Choose 'Copy Playlist Link' then send it to your friends.
Step 1. Tap 'Your Library' > 'Playlists' and select one you want to make Collaborative.
Step 2. Tap in the top-right corner > 'Make Collaborative'
Step 3. Choose the top-right corner again
Step 4. Choose 'Copy Link', then distribute to your friends.
Note: This Collaborative Playlists feature isn't available on mobile unless you have a Premium account.
See also: Spotify Free VS Premium
If you want to download and back up Spotify playlists for personal use, but you do not have a Spotify Premium account, you can try Spotify music downloader. Navigate to the TunesKit Spotify Music Converter free (Mac or Windows), select the 'Download' option to install the Spotify converter. Let's go to download Spotify music for free with it.
For more: https://www.tuneskit.com/spotify-music-tips/collaborative-playlist-spotify.html