The first time and before you authorize, the plugin is loaded in try out mode (figure 1).
To authorize you can either press the "Learn How" Button at the bottom of the plugin or the gear icon at the upper right side. This will take you to the registration view (figure 2).
You authorize the plug-in by following steps 1 and 2.
The explicite steps are:
When the plugin is authorized you can get back to the main view by clicking the gear icon at the upper right side.