Are you a Family or Duo member, but not the admin of the account?

Yes,im in a family and im not the admin 

Do you have a separate login and account, or are you on a profile created by the admin and using his login? If the former, you could try to leave the family and use the Sharing Preferences page of your free account then where you might be able to see the Last.fm connect button and enable it. Afterwards you can join the family again, and scrobbling should still work.

At least someone with the same problem recently described that this method has worked for him, but I did not test it myself.