My family has the Apple Music family plan. Before purchasing it, we each had our own iTunes playlists on our individual devices. Now we can only access the playlists of the account holder. How do we get our playlists back?

You need to set up Family Sharing which will allow you to share your Apple Music Family subscription while each member still being able to use their own Apple ID. I am assuming you have simply signed into all the devices with the Apple ID that pays for the family subscription, which would add that persons playlists and data to everyone’s devices.

You can set up Family Sharing by following this help article: https://support.apple.com/en-gb/HT201060

You can find more help with Apple Music and Family Sharing by going to: https://support.apple.com/en-gb/HT205595

However depending on how long iCloud retains data, when you stop paying the individual Apple Music subscriptions, the playlists and data associated with that subscription may have been permanently deleted.