You’re likely on macOS Monterey, Ventura, or Sonoma. There is no official way to backdate GarageBand on a newer OS. Either use the latest version (which is excellent) or dual-boot an older macOS partition.
If your computer is on a newer macOS operating system (like Ventura or Sonoma), you cannot directly request a step back to version 10.4.1. You must download the absolute latest compatible build: Open the on your Mac. Search for GarageBand in the search bar. Garageband 10.4.1 Download
Released in late 2020 alongside macOS Big Sur, GarageBand 10.4.1 wasn't just a minor bug-fix patch. It introduced significant workflow enhancements that professional and amateur users still appreciate today. You’re likely on macOS Monterey, Ventura, or Sonoma