If it asks for "Additional Setup," click and let the phone reboot one last time. 🛡️ Alternatives for Android 4.4.2
Corrupted Magisk database. Fix: Clear app data: Settings > Apps > Magisk Manager > Clear Data . Then reboot.
This was the gold standard for rooting Android 4.4.2. You can often find flashable ZIP files for SuperSU on the XDA Forums specifically for your device model.
Android 4.4.2 (KitKat) not supported? · Issue #9018 - GitHub