iPad Air not appearing on Mac for music transfer

Check Finder > Settings…

Make sure that there is a checkmark besides "CDs, DVDs, and iOS Devices" in the General tab.

Check your cable

If the Finder Settings are set up correctly, and your iPad does not appear in the sidebar of Finder windows after you plug it in, the problem may be the cable. Some "charging" cables only connect pins required for 5V power and do not connect data pins. If you use such a cable, your iPad may charge off your Mac, but the two will not see each other. Replace the cable with one that does carry data to fix this.

Also see: Sync your iPhone, iPad, or iPod using your computer - Apple Support

You want a cable that has the right type of connector on each end and whose description says that it can carry data. (Or an equivalent combination of cables and adapters, but if you're getting a new cable, why bother with that, when you can do things with a single cable?)

I could be mistaken, but I believe all iPads released in 2025 would have had a USB-C port (not a Lightning one). Your computer probably has either a USB-A port, a USB-C port, or both.

So you probably want a USB-C to USB-C cable, or a USB-C to USB-A cable, that is advertised as being able to carry data.