GarageBand not working for High Sierra

Hi, I have a MacBook with High Sierra installed on it, and I go to the App Store to look for GarageBand, and I clicked on get, and when I click on Install App, it says GarageBand could not be installed on High Sierra, please upgrade to macOS Big Sur. When I upgrade the software, like iTunes, Security Options, and others, my Mac reboots, and when it finishes installing, it pops up with a black screen saying it could not find something. Can someone help me, or tell me what to do?