Pictured is the original switch.

I watched several videos before attempting the install.  This switch is the hot one.

Yes it has two black wires.  The one that is on the same side of the ground has the power.  The other black wire on the bottom on the same side as the red one, goes to the neutral bundle in the back.

With the HS210, I connected the power to the black screw.  I connected the red to the screw on top, nearest the black screw.  I attached the 2nd black/neutral wire to the other top screw.  I capped of the grounds together (green wire coming out of the HS210), and the white cable I added to the neutral bundle.

The unit got power and I was able add the switch to the app.  It just did not work.  Neither did the 'dumb' switch.  I tried several combinations of the neutrals with no luck.