It appears you aren't signed into your X-Aviation account through Gizmo in-sim, and thus the plugin isn't able to activate. Sometimes on multi-monitor setups the Gizmo sign-in dialog can appear off screen. To circumvent this, load X-Plane with only the single primary display (unplug any additional monitors and RealSimGear hardware) connected to your computer and it should present itself. Following that, you can restore your displays to as they were before.