Because the user root has no password you can‘t connect with this user root to the MoodleBox.
You must do the following. For a file transfer with sftp you can use FileZilla on Linux, macOS or Windows. It‘s very easy to use. The server for sftp is moodlebox.home, the user is moodlebox and the password is Moodlebox4$. You upload files to the personal folder /home/moodlebox.
Now connect to the MoodleBox via ssh in a terminal.
ssh email@example.com The user is moodlebox again. You are landing in the personal folder again. You should see you uploaded files there. Now you can change to the user root by
sudo su and move all files to other places. You also can edit configuration files with