You should never use a steam cleaner or steam mop on a Vinyl plank floor since the dripping water and the steamy hot water can actually damage your Vinyl Plank Floor by warping it.
The steam also has the potential to dull the finish of the Vinyl Plank flooring as well.
The best way of cleaning a Vinyl Plank floor is to use a regular mop and add a cup of vinegar to the mop water.
The Vinegar and water will naturally clean your Vinyl Plank floor without harsh chemicals that could damage your floor.