So to clarify, at each of your two switch boxes, there is only one 3-wire romex connected to the switch? If that’s the case, then you probably have power to the light first. And your correct that the Inovelli diagrams don’t show wiring for this configuration.
Can you get at the light to confirm? If you have power to the light, I’d expect to see a three-wire romex there where probably the black is constantly hot.
If that’s the case, the wiring configuration is described in this thread.
The diagrams in that thread might be a bit confusing because of another devices in the box, so we can try to figure it out here if you can’t make sense of that.
Can you post pictures of both boxes with the switches pulled out so that we can see both the wiring on the switches AND what’s inside the boxes?