Quote - "You can set Spectral Clouds to be influenced by lights in your scene."

It's not exactly like this. In fact, it's the other way around: you have to set lights to influence clouds. You do so by clicking on the little cloud icon on the object properties panel when your light source is selected. The object properties panel is on the right side of the screen, the top section.
If you don't click on this icon, the light won't influence clouds.