WIFI switch and a lot of wires. How to?

[Callopsitte]

First, sorry if I'm not in the correxct thread.

I'm trying to replace an old switch with a WIFI switch and cannot seem to do it right. There are three electric wires (each wire meaning a neutral, a load and a ground) coming out of the box and the old switch has two black wires to it (I figured which one was the load using my electrical pen). The new (wifi) switch that I would like to install instead has YL/RD and Load connection on one side. On the other side is AC-L (which I figure is load) and AC-N (which I figure is neutral) and of course ground). I tried taking the load off the old switch put it in AC-L and Neutral and put it in AC-N in wifi switch. The switch seemed to work but the lights would not light up.

I made a drawing of the bathroom electricals so you can understand better (hopefully). As you'll see, the three white (neutrals) from the box are twisted together. Two blacks from the box and the Load of the switch are twisted together. Then one black from the box goes to the neutral of the switch. I also uploaded the pdf instructions of the wifi switch.

What you need to know is that this switch controls one set of lights. From the same breaker and in that room there is another set of lights working with another switch, also a GFCI outlet and just outside that room another light working with another switch.

Thank you very much for helping a "I only understand two wires switch only" lol.

 

[Avo Mk8]

Firstly I would suggest that of the three sets of cables, they are not all 'incoming'. There might be one cable (of 3 wires) bringing in permanent power, and then the other two cables go to the load (eg if there are two or more lights on this switch).. Or possibly the other way round, two cables with permanent power (one of which goes somewhere else to power another lighting circuit), and one for the load.
Your old light switch is in series with the load, and normally (at least in the UK) the switch is in the live (i guess you say hot) wire, so one switch wire is permanently hot, and the other connected to the load becomes hot when you close the switch.
When you say you used a pen tester to identify the load, do you mean it lit up on side that stayed live whatever the position of the light switch, and you decided the other was the load?

I would have thought your neutral wire, needed for the wi-fi switch, is the group of whites, and is neither of the black wires going to the switch.
For the new wi-fi switch:y7
The AC-L is for permanent live.
And AC-N is for neutral.
I think your sketch is incorrect, the wire labelled Neutral (black) is surely permanent hot? Or the two blacks are the other way round, and the one you labelled Load is permanent hot.

Below is how you should be wiring it (assuming not 3-way, ie there's another switch for these lights - you don't have a 3-way switch)