Question' Installing a 3way switch Do i need to install two 3-way switches, one on each end for this to work? if so is the netural wire (white) required for the second switch? The first switch has all

Just got the new KS230 3 Way Dimmers. I purchased 2 sets first set the secondary switch will not work. Second set the main switch will not connect to the app. No TPlink appears. Spent the whole day tr