In a working phone Unauthorised can crop up due to the user missing this notification
So be sure to pull down the Notifications, and tap on the reference to USB.
The support pages are:
- Enable USB Debugging and OEM Unlock
- Fix unauthorized device error in adb
- It is this second link which covers your error.
All of my advice since Post #10 has favoured using the regular install page and not the eosinstaller.
