If you have ever downloaded GarageBand in the past using your Apple ID—even on a different, newer Mac—Apple allows you to download the last compatible version for your current OS. Step-by-Step Installation: Open the on your El Capitan Mac. Click on the Purchased tab at the top of the window. Sign in with the Apple ID you used previously.
No. GarageBand 10.4 and newer require macOS 10.13 High Sierra or later. El Capitan users are limited to versions 10.2 or older. Garageband Mac Os X El Capitan 10.11.6 Download
When installing older versions of GarageBand, the app may try to download its core instrument library from Apple's servers. If those servers are offline for older versions, some instruments might be missing. If you have ever downloaded GarageBand in the