Step 2: Wiring in the controller
The way the temperature controller work is by cutting on and off the flow from the hot to either a heating or cooling element. Both circuits are normally open. When the temperature gets too hot, it will close the circuit and allow electricity to flow to the cooling element (the freezer). If I was using the freezer as a fermenter I might also have a heating element like a small ceramic heater or dehydrator connected that would be turned on when the temperature dropped too much.
To wire it up, the incoming (black cord in my case) hot and neutral get connected to the appropriate posts. Here the hot went to post 5 and the neutral to post 6, as shown on the diagram. The hot also needs to be connected to the post to switching portion before reaching the heating/cooling elements. Because post 1 and 5 both need to be connected to the incoming hot, you need to either pigtail a split in or do what I did an jumper a second short wire between the two. Next you need to connect the outgoing post shown going to the cooling element to the line that goes to the freezer (white cord here). Although the diagram shown this to be post 2, I found this to be a misprint and that post 3 actually is for the cooling element. Initially the freezer came on when the temperature was too low, which could have had disastrous implications if I didn't catch the mistake. Post 7 and 8 get connected to the included temperature probe, it doesn't matter which leg connects to which post. The neutral going to the freezer should get attached to post 6 along with the neutral coming from the outlet. The grounds don't actually connect to the controller and should be joined directly to each other.
Before sealing everything up, plug in the freezer to make sure it is all working as intended. To set the temperature, press set, use the up/down arrows to select the temp, then press reset. Test both when the probe it too hot or too cold. You can hold it against an ice cube if you need to cool it down.