If you have downloaded GarageBand in the past under your Apple ID, you might be able to find version 10.4.1 specifically:
If you want, I can:
: While the App Store may state it requires macOS 11.0 or later, it has historically supported macOS 10.13.6+ through specific update packages. Official Source : Download only from the Official Apple GarageBand Page Mac App Store Legacy Hardware garageband 1041 download new