Adding a comment here, because I was pulling my hair out and not finding anything on the Internet with how this can be done specifically

I have Kasa HS230. I bought two of the version 1.0 kits. 

I was able to make this work on a four way, but it does require using one main and 2 satellites. So you’re going to buy two kits and have an extra main that is worthless at the end of the day. 

Main gets wired up on the line side as normal.

The satellite on the other three way switch gets wired up as normal. 

In the middle, where I have four wires coming in for my dumb four way switch I wired up an additional satellite. In my installation, my four-way travelers coming into that four way switch were white and red (4 wires total with a white and red coming from each 3-way switch). I have the whites both connected to the Traveler 1 and reds both connected to Traveler 2/load. Red and white Colors match the other Traveler 1 and 2 on the Main and other satellite. 

Everything works perfectly.