Here is what you need to know to get you going:
In a 4+ way switch configuration, you will have 3-way (i.e. 3 terminals) switches on both ends with 4-way (i.e. 4 terminals) switches in the middle. Power (the Line) starts at one end at one of the 3-way switches. The light (Load) can either be in that same box or be at the other end.
You posted pics of one of the 3-ways. According to you and verified by the pics, that terminals on that 3-way switch are all connected to that one Romex. That suggests to me that you have a Line and Load in the same box configuration.
So based on the limited information you’ve provided, I think that your Line and Load are in the OTHER 3-way switch box. That’s where you will put the Inovelli. If I am correct, you will see three Romex involved. You’ll have one 2-wire that is a hot and neutral, one 2-wire going to the light (load) and one 3-wire going to the other switch.
This:
