: Users have reported success by AirDropping the installed app from another Mac running the same OS version (e.g., from one Catalina Mac to another). System Requirements for 10.3.5
: Sign in with your Apple ID on a newer Mac that can run the latest version, "buy" (download) GarageBand there, then return to your older Mac. It should now appear in your purchase history for a "last compatible" download. garageband 1035 dmg link
(usually in the bottom-left corner). Locate GarageBand in your list of "Purchased" apps. Click the Cloud icon next to it. : Users have reported success by AirDropping the
If you have never linked GarageBand to your Apple ID, it will not appear in your purchase history. Apple does not officially provide older DMG installers to new users. A common workaround is: (usually in the bottom-left corner)