To answer your question, JoaoF:
Render Shadows - Bool. If true, shadows will be outputted. If false, I believe the output from shadows will return a constant value of 1.
Light vector - 3 Constant. The direction of the light angle, normalized. 0,0,1 will have the light from above. 1,0,0 will have the light from the side. -1,0,0 switches sides.
Shadow Steps - 1 Constant. Number of steps to consider for shadow calculations. You don’t need to be too high, but the higher the clearer. And more expensive.
Shadow Pneumbra - 1 Constant. 1 is a sharp shadow. Higher is sharper. Lower is softer. 0 is completely soft.