In the workbench we only use a single directional lights source.

step1 do the prepass (we need the depth buffer)
step2 generate the shadow volume mesh (geom shader) (world space coordinates => viewport space coordinates
step3 set stencil when shadow is fragment is near the depth
step4 use the stencil to draw the pixels in shadow
step5 use the stencil to draw the lit pixels

Note. Only do this when shadow is enabled.