I have tried to follow the instructions from the link https://highonandroid.com/android-root-101/how-to-unlock-bootloader-on-any-android-android-root-101-1/ to unlock the bootloader. It fails with the following error.
C:\Users\S\Downloads\fastboot>adb reboot bootloader
- daemon not running; starting now at tcp:5037
- daemon started successfully
error: device unauthorized.
This adb server’s $ADB_VENDOR_KEYS is not set
Try ‘adb kill-server’ if that seems wrong.
Otherwise check for a confirmation dialog on your device.
Any thoughts or help please would be appreciated.