How to Activate Muse Sounds

I installed the Keyboard Muse Sounds using MuseHub and MuseScore 4.0. However, when I go to View/Playback Setup, I see MuseScore Basic and Muse Sounds listed, but Muse Sounds is greyed out and it says it's inactive. MuseScoreBasic is selected and set as the default, but I don't see any way to activate Muse Sounds or to make it the default profile. I tried turning off having MuseScore Basic as the default for new scores, and created a new one. This time it listed both Basic and Muse Sounds profiles, but the only one I could activate was MuseScore Basic.

How can I activate Muse Sounds?

I've uninstalled and reinstalled both MuseHub and MuseScore 4 several times but it seems to make no difference.

I'm on a MacBook Air running MacOS Monterey v12.6.5, so I'm running the Mac version of MuseHub and MuseScore.

Any help would be appreciated.

Thanks.