I'm trying to replace a light switch with a new z wave smart switch. Specifically, the old light switch has 2 black wires and a ground wire attached to it and it is the only switch that controls 1 LED light. The new z wave switch is an Eaton RF9601 and it has 4 output wires: white, black, red and blue. This is the wiring diagram provided with the switch: 
And I am a bit confused with how (or if) my scenario is compatible with this z wave switch. I capped the blue switch output and connected the green output to the existing ground wire I had, and connected the black output to one of the existing black wires. The other black wire is what I wasn't sure how to connect. I tried connecting it to the red output and the light comes on but was very dim, when connected to the white output the light was completely off. Any suggestions for the correct way to wire this?
A = Black Wire
B = Ground
C = Black Wire
D = Neutral?
When connected with A -> Red, B -> Green, C -> Black, D-> White and the light does not come on at all when power is turned back on.
Based on suggestions in comments I tried connecting A -> Black, B -> Green, C -> Red, D-> White and the light flashes and immediately turns off when the power to the switch is turned on.
Adding another picture of box to help clarify:
Turquoise circles are ends of white wire (D) and red circles are ends of black wires coming into box.
Best Answer
The new smart switch requires a neutral so unless you have a couple white wires wire-nutted together in the box with the switch, you're out of luck using that switch. You'll need to get a switch that doesn't require a neutral.
If you have only two true black wires in the switch box, chances are you have conduit and you could pull some THHN from the ceiling to the switch and bring in a neutral but we'd need more pictures to verify that.