The official software support for the SM-G900T ended years ago, leaving it stuck on Android 6.0.1 (Marshmallow). By moving to a custom ROM, you gain:
Receive the latest monthly security patches.
If you are ready to start, I can help you find the or provide a troubleshooting guide for specific error codes. How to root the device using Magisk after flashing? Where to find the most recent build for Android 11 or 12?