You can find more information about how to configure your Syncbox here.
If the Intel NUC is connected to a monitor and a mouse, LabSat Real-Time+ can be the SatGen Real-Time+ user interface and give you the ability to manually configure the simulation output. You can, for example, set the number of simulated constellations, adjust the attenuation, or enable an external reference clock.
You can find more information about how to configure your NMEA Test Utility here.