There is no direct download link that works reliably in a browser for this OS. The only method is using the Mac App Store’s legacy mechanism.

: Temporarily disconnect from the internet and set your system date back to early 2012 via System Preferences > Date & Time . This makes the old installer's certificate valid again. Summary of Compatible Versions OS Version Typical Compatible GarageBand Version El Capitan (10.11.6) GarageBand 10.1.1 (or late 6.0.5 versions)

Drop your files here