Hi Andrew,
With your controller and fridge, it's my opinion that you may be making things difficult for yourself by tapping into the compressor connections. I can highly recommend that you pop out the fridge's original temperature "dial" control unit, disconnect the two wires that run to and from this unit, extend these two wires and connect them to terminals 7 & 8 of your Inkbird. Then splice into the mains supply cable before it connects to original fridge components, tee into the L & N wires to provide extensions that you can then connect to terminals 1 & 2 on your inkbird. The fridges original temp probe will then be isolated, the light will still work and the fridge will then be fully controlled by the Inkbird once you have installed the Inkbird probe and wired to terminals 3 & 4. It's a quick, safe and reliable method that will avoid the consequential risks of bad wiring.
If there is a reason why you feel that tapping the compressor wiring is preferable to the above solution, let me know, and I will see if I can suggest a different method to acheive this.
Really hope this helps, and would it would be great to hear how you got on if my suggestion is used. Good Luck
Rupert, November 2019