Apple TV 4k audio to my Onkyo Zone 2

I understand this is a continuation of an old thread and I understand that Zone 2 will only accept analog. As suggested in the old thread I purchased the analog converter box from Amazon but need a little more clarification as to how to connect to proper input jacks for my TX-RZ50 AVR. A previous poster indicated that I need to connect the RCA cable to my input Zone 2 but looking at the back of my unit it is unclear which input jacks that would be. Just to clarify my Zone 2 works fine using NET input etc but my problem is only with inputs coming from the Apple TV 4k box. Also, I don't want to mess up the signals when playing in my normal main zone. Before I start experimenting, can anyone provide some clarification?