At the top of Lumatone Editor, you'll find a toggle between Live Mode and Offline mode:
Offline mode allows for the creation and editing of mappings without a Lumatone present, and defaults to this mode if a Lumatone is not detected. Mappings can be loaded from a file, and saved to a file, but you won’t be able to send mappings to Lumatone until you connect it. You will also find offline mode handy even if you have a Lumatone present, but for some reason don't want your work to update in real time on your instrument.
For everything else, there's Live Mode. Whenever your Lumatone is connected, Lumatone Editor defaults there. In most cases, this is the most desirable way to work. You can see the result of your edits on your instrument in real time, test your mapping as you create, and save your mapping to a preset button on Lumatone when you’re ready.