2015 C - aftermarket cruise - errors

I've got a 2015 C. Just installed an aftermarket cruise control:

Rostra Part Number: 250-1836. I had to do not only the basic installation, but also the ECM and Ground Harnesses as well. All assembled just fine and when I started the car and pressed the cruise on/off button, I was able to toggle the cruise control icon on the dash from on to off.

I then took the car for a spin, all went fine until I pressed the joystick down to engage the cruise for a test. The Alert triangle (with the "!" in it) and the traction control off indicator (car with swerving skid marks) immediately turned on and the following message popped up on my dash: "Check Cruise Control System". Additionally, the cruise control icon turned off. After this initial problem, it is impossible to re-engage the cruise control icon. Every time I try, the same error pops up. Regardless of what I do, the traction control icon will not turn off (even when I press the actual on/off switch for traction).

When I turn off the vehicle and turn it back on... I can once again toggle the cruise control icon, but if I try to engage it while moving... the error comes back. Attempting to engage cruise control while at a stop does not trigger this problem.

Turning the car off and on does not effect the traction control light. That is now permanently on (indicating that TC is off). Disconnecting the cruise control and turning the car off and on did not reset the traction control light either.

So using Rostra website form #5350, I followed the trouble shooting guide and tested voltage on the unit. I've found that the voltage is consistently high. Below is the "Position - Suggested Voltage - Actual Voltage" readouts.

Key On - 12v - 14.01v
Switch "On" - 0v - 0.02v (negligible)
Switch "Set" - 6v - 6.78v
Switch "Resume" - 3v - 3.70v

I'm wondering if the higher voltage is effecting the signal, but am not sure if it is negligible at those numbers.

Can anyone advise what my next steps should be? Have you had this problem when installing.

Thanks!