Reading up more it seems it should work in the gang box. This is a one-pole switch though there's a 3-pole in the gang box with it.

Here is my situation.

Previous switch:

• Had one live black wire that came from the next switch over and wrapped around the load screw and CONTINUED into the box. Just one continuous wire with the middle stripped out around the screw.
• Had one neutral BLACK (not sure why it isn't white) wire coming from the box into the neutral screw
• Wasn't grounded.

HS200 installation:

• Connected the two black HS200 load wires to the stripped out load wire using a pig tail (was kind of difficult given the continuous wire).
• Connected the black neutral wire to the HS200 white neutral wire.
• Found a copper wire and grounded to the green HS200 wire.

The circuit works now (the other two switches in the gang work). However, when I turn on the HS200 only a small glow on the first of two bulbs appears. The Wifi is fine, and I've tried it on two HS200s with the same result. Something appears to be wrong with the wiring I did.

Chat support told me to call an electrician, but that would cost 3 times what the switch costs so I would just send back the switch. Any ideas?

Thanks in advance!

@Sleepy 

Thank you for the additional information This allowed me to know the issue.  You have it wired up incorrectly.  In the 3-gang box you describe the HS200 will not work.   This is because the Load and Live wires must be seperate in order to function properly.  The issue you are experiacing is exactly what happens when they are spliced together.  For the HS200 to work properly there should be 2 live wires,  one working as the load and one working as the power, and a netural wire.  the Ground is good but optional. Support's recomendation for an electriian is standard as we do not have electrical wiring training, although in this case should have caught that and told you what the problem was.  

Best Regards

Carl | TP-Link Support