iMovie and non-Apple audio on the iMac

I'm creating a movie on iMovie using the iMac. The Apple-installed soundtracks/sound effects in iMovie iMac are limited to those found on the iPad. It is not possible to transfer the Apple-installed soundtracks/sound effects from the iPad to the iMac.

So...

Is anyone aware of royalty or copyright free music in Apple Music that can be added to iMovie iMac? I found some "royalty free" and "copyright free" music in Apple Music. I added them to my iTunes library. Unfortunately, iMovie Mac doesn't allow me to use them.