I recently downloaded this excellent app/program for my MacBook.
It allows you to listen to virtually any music you want, as long as you have a net connection, for free. They put ads in every 4-5 songs, but that is a small price to pay. Another nice feature is the ‘new’ music. It allows you to see what is current, what people are listening to. Another good feature that I like is that based on your listening habits, it suggests artists you may like.
There is a paid version which allows you to store offline the music you want, and has no ads.