Transfer music

Hi LWhiteLayton,

For help with transferring and syncing content between your iPhone and iMac, check out the steps below found in the article here: Sync content between your Mac and iPhone, iPad, or iPod touch

"Sync all items of a content type

1. Connect your device to your Mac.
2. You can connect your device using a USB or USB-C cable or using a Wi-Fi connection. See Sync content between your Mac and iPhone, iPad, or iPod touch over Wi-Fi.
3. In the Finder  on your Mac, select the device in the Finder sidebar.
4. 
5. If you connect your device to your Mac using a USB cable and don’t see the device in the Finder sidebar, see If your device doesn’t appear in the sidebar. 
6. Click the type of content you want to sync in the button bar.
7. 
8. Note: If you use iCloud Photos and Apple Music, your photos and music are synced automatically using iCloud. When you click Music or Photos, no options appear for syncing.
9. Select the “Sync [content type] onto [device name]” checkbox to turn on syncing for that type of item. For example, select the “Sync movies onto [device name]” checkbox to sync your movies.
10. 
11. With the checkbox selected, syncing is set to transfer all items of that type to your device. 
12. Repeat steps 3 and 4 for each type of content you want to sync.
13. The bar at the bottom of the window shows how much free space remains on your device after you sync. Move the pointer over the bar to view details about the content you’re syncing.
14. When you’re ready to sync, click Apply."

You can also find helpful information here: Sync content between your Mac and iPhone, iPad, or iPod touch

If you have an Apple Music membership, check out the steps here: Use Sync Library to access your music library across your devices - Apple Support

Cheers.