You shouldn't need to connect the ribbon cable to anything, just push it back inside the scale and replace the plate you remove with the plastic piece with the circuit boards on it. The cable that hangs out of the new part plugs into the serial port above it. You plug the trickler into port 1 and the thrower into port 2.
The new power pack plugs in to replace the original one for the scales as they draw more power running the motors on the devices. I tried with the original and got a Lb (I imagine low battery) and the scale stopped reading for a bit. The new one fixes that. There's no separate power to the Autotrickler.
Download the autotrickler app and try to connect, if it doesn't find the autotrickler you may need to fit the jumper cable to provide power to the unit (it plugs into one port on the ribbon cable inside and then onto the bottom of the circuit board). I had to fit the jumper cable on mine but it is an older FX200i scale. If you plug the circuit board in and turn the power on before you screw it together you should see a blinking light on the board which would indicate that you don't need the jumper cable.
Changing the settings on the scale is simple, just follow the instructions and it works. If you make a mistake you can repeat the steps to check and fix what went wrong.
The whole process from start to finish took around 15 minutes on mine including having to remove the circuit board unit again and fit the jumper cable. I only bought the trickler and love it, I might have to buy the thrower now because knowing I could be using it instead of manually throwing powder is bugging me.
Getting the centering piece for the shot glass in the right spot is a bit of trial and error, just sticky tape it on until you work out the right spot and then use the double sided tape to attach it more permanently.