Start at the end of the ladder then put two feet out to the side and then one foot in the next hole, then two feet out again then put the other foot in and repeat down the ladder alternating which foot goes in the middle each time.
This exercise is based on the old playground game Hopscotch.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.