: It is the last version compatible with devices that cannot update past iOS 5.1.1, such as the 1st Gen iPad. User Interface Preference
You might wonder why anyone would go through the hassle of sideloading an IPA instead of just downloading the free current version from the App Store. Here are the main drivers.
A local Wi-Fi and Bluetooth protocol allowing up to four iOS devices to sync wirelessly and record a multi-track session in real-time. Why Musicians Hunt for the GarageBand 1.4.1 IPA
If using Sideloadly, consider creating a secondary, free "burner" Apple ID solely for signing legacy apps to protect your primary account privacy. Final Thoughts
So, you got it working. Why use 1.4.1 instead of the modern GarageBand?
Version 1.4.1 relied on downloadable content from Apple’s old CDN. Those URLs are dead. You may only get the base instruments (Grand Piano, Classic Rock Kit). Advanced content is no longer downloadable.