So Daz3D tries to make it's camera/lighting behave like real camera lighting. Which means we have to worry about light properties like Flux and Temperature. So if you were trying to mix your spotlight with the default scene lighting, I'm willing to bet no matter how much you jacked up the intensity on one or the other, it wouldn't behave for you.
Real point, while throwing a spotlight on a scene and calling it a day will technically "light" it, it's probably not going to be very interesting. To light a scene traditionally, we need some combination of Key (the spotlight counts), Fill, and Rim. Preferably not all in the exact same color/intensity. Should have similar Flux/Temp though unless we want something like a window with a view of daylight to darken the rest of the scene.
For a quick cheat, can use Aurous Lighting. Can be found here:
Egyptian Mega Bundle. Will automatically remove any existing light and give the artist a good set of presets.