If you’ve downloaded GarageBand before, go to the App Store > Purchased tab. It may offer you the "last compatible version".

If you cannot use the App Store method, users often turn to third-party repositories, though these carry higher security risks: Archive.org

, the native Apple plugin format, allowing users to integrate high-end third-party instruments and effects from developers like Waves and Native Instruments. Finding and Installing the .dmg

: It offers the polished interface introduced in version 10.3 without the higher system requirements of later versions.