401 Error on scrobbling to last.fm with non-admin account

[shondreas]

I also found this:

Does Last.fm scrobble plays from another account accessing your shared server?

No, because these people are using their own plex.tv account to access your server. The last.fm account is linked to your plex account, not to your server. No, only content played from audio libraries will get scrobbled (which may include audio books as well).

So does your user have their own plex account or are they a “managed” user in your Home? Looks like it should work if they have their own plex account.