Legal Question in Technology Law in California

You need two (2) documents for each song included. The first document is called a "Synchronization License", which covers the rights in the musical composition. The second is called a "Master License", which covers the recording of the song. Since the composition and master are likely owned by different parties (the songwriter or publisher on one hand, and the record company on the other), there's no one-stop shopping.

Expect to pay something for the licenses you seek. If you're doing a 'festival only' license, for a school project, the fees will be very low... you MIGHT even be able to get a free or 'gratis' license, but doing so will take a loooong time. These companies are in business to make money... so requests for freebies go to the bottom of the pile.

If you need help, there are consultants, music licensing companies, and attorneys (myself included) who do this kind of thing all the time.