Woodie Roach Colony HELP PLEASE!

Wondering if anyone can help me with my Woodie Roach colony.

I ordered 500 small and 500 mixed about a month ago. Put them in a 60l storage container with the lid cut out and mesh glued on. Set up eggcartons in there and fed cat food (Kirklands grain free if that matters lol) and then fresh grated carrots daily and fresh vege scraps like Rocket, pumpkin and zucchini.

They have clearly been breeding but some have died and despite my best efforts to clean it out 2 weeks ago, it STINKS. I am not even exaggerating. It stunk so bad that yesterday while doing a full clean out I was heaving and gagging. It was so fricken disgusting.

I am trying to problem solve why it is so rank. I am thinking too much moisture? Too much humidity (Brisbane and in the garage)? Maybe not enough airflow? Garage isnt exactly known for airflow. Too much vege's being fed maybe which adds to moisture?

I have to be honest, in an attempt to lessen and absorb the stench a little I put cat litter in there. Its gonna make further clean outs next to impossible BUT it helped. It absorbed the smell and should help absorb the moisture if that is indeed the issue.

I need help. PLEASE! I chose woodies as they were meant to be low maintenance and NOT smell and instead they are so bad I want to gas them all and throw them out.

Thanks in advance.

The stench is concerning. That sounds like bacteria buildup from decomposition which could be from rotting food or mold which would be harmful. I wouldn't add cat litter but you may want to move them to a new/clean bin and give it another start. I'd make sure it's well ventilated with perhaps a completely mesh top. I would limit the fruit and veg you're adding to ensure it is all eaten or dries up before adding more to help prevent mold and moisture buildup. If you are still having trouble with humidity after that you may want to introduce a computer case fan or something similar to help increase airflow.