The Last Song on El Capitan
xattr -cr /Applications/GarageBand.appAudio interface and latency
Introduction: The Legacy User’s Dilemma Garageband Mac Os X El Capitan 10.11.6 Download
Because Apple no longer sells older standalone versions of GarageBand, your options depend on your account history:
If you have never owned GarageBand on your Apple ID, it won't appear in your Purchases. You can "buy" it (it's free) on a newer Mac to make it show up in your history. The Last Song on El Capitan
This article provides a definitive, step-by-step guide on how to find, download, install, and troubleshoot GarageBand on El Capitan.
Verdict: For basic podcast editing, guitar recording, or MIDI piano, 10.1.6 is perfectly capable. For EDM production using loops, you need a newer OS. Open Terminal (found in Applications > Utilities)
Bottom Line: Apple hasn't forgotten you. While you can't run the newest features, the "El Capitan Edition" of GarageBand remains a powerful, free DAW that turns that old white MacBook into a viable recording rig.