Sails would not work, or do anything useful for a lighter than air aircraft.

A lighter than air aircraft with no propulsion will travel in the direction of the wind at the speed of the wind. No amount of sails will make it go any faster or in any other direction. So, there would be no point in putting sails on such an aircraft.

Sails work on ships because the hull of the ship is in the water, not in the air. Sails help a ship go downwind faster than if there were no sails, because they use propulsion from the wind to overcome the drag of the hull in the water. Sails allow ships to sail across the wind, or upwind (tacking), because the resistance of the hull in the water prevents the ship (retards the ship) from being forced directly downwind by the sails and allows the force from the sails to be translated into cross wind or upwind progress.

Airships, having no such resistance from another medium, will travel down wind at the speed of the wind no matter what sails are set, and even if no sails are used. (Unless, they have some other source of propulsion, such as an engine and propellers.)