With AirDrop it's easy to do, and no third party apps are needed. On the Mac, go into finder and from the menu bar, pick "Go" and then "AirDrop". This should open the AirDrop window on your Mac. At the bottom of the window, change "Allow me to be discovered by" to "Everyone". On the iPhone, find the music you want to transfer. (I usually do pictures right from Photos app, but suppose you can find your music in the Files app, if not elsewhere) Long press on it, and pick "Share". In the pane that opens, tap on the AirDrop icon". You should see an icon for your Mac. Tap it. Then, back on your Mac, you should see the request to share the file or folder. Just press "Accept" to start the transfer.