Content restriction on standalone Apple Watch

We got an Apple Watch as a device for our daughter. She has one with built in cellular and doesn't have a Phone so she is using it standalone. We weren't able to make Spotify work on it because it requires a phone for it to be connected to. We then tried switching to an Apple Music family plan, which allows her to find and play music on the device (although you can't play the music through the built-in speakers for some reason).

My issue is there doesn't seem to be a way to restrict explicit music for her in this setup. Spotify lets you set this on the account, and if I go to music.apple.com online with her account I can set the restriction, but even in the site it says that content restriction only works in the web version.

How do I enable content restriction in a standalone watch setup like this? On the watch I can't find any settings to enable these parental controls, and setting these on the account via web doesn't seem to restrict the device account in any way.