Diagram for wiring sonoff to bathroom fan?

I recently eliminated a combo heat, vent and light fan in my bathroom.

There were two switches before, one for vent and another for light+heat. To the new fan I have a 4 wires (load, neutral, ground, traveler). The traveler is currently capped off and I have it on a simple switch.

I would like to add a sonoff relay and maybe a humidity sensor as well. I have room in the switch box, or the ceiling for the sonoff. Is there any suggested setup for retrofitting this? Should I just leave the traveler wire capped? A schematic or diagram would be super helpful.

If you can’t identify and wire this simple circuit yourself it may be best for you to call an electrician.

If you can identify the wires, there are wiring diagrams on the sonoff site that should give you all the information you need.