Hi mvmai...,
It looks like your external 2TB USB unit needs to be formatted. The B2 will only recognise a drive that is 'FAT32' formatted. Notr that the 'Format' function will delete any existing data on the drive, so you should copy any existing date on that drive to a safe location.
To format the USB drive, from the B2's front panel knob, select:
'Settings' --> 'Maintenance' --> 'Format USB C' (if the device is plugged into USB C') OR 'Format USB A' if the device is plugged into USB A.
NOTE: Do not select the 'Format HDD' function under any circumstances; this function will delete all of your music collection from the B2.
You should see a message briefly appear, 'Partitioning', only for a second or two, then you should see a further message 'Formatting' which should remain on the display for up to 3 minutes.
After this is complete, if you go back to the 'USB Functions' menu, then you should be able to select 'Export to C' OR 'Export to A' depending on the USB port that you are using.
If the 'Formatting' message only flashes up for a few seconds, then the format has failed. This occasionally occurs for unknown reasons currently, so if this happens post back here and we will try and help you further.
Regards,
Peter.