Hey! I’m a beginner as well, but I think I can answer your question.
The track is too repetitive, there is no development. I think you did this on purpose since you mentioned “loop” in your post. If you want to create a loop, you should just upload the main unique part and not just repeat it many times. But it should be loop-ready which means that if you put the track on repeat, it gives you an illusion that you’re listening to a never ending track. For example: https://audiojungle.net/item/crime/19561004
Since you uploaded a track with length of 2:48, the reviewer expects a full track with a development meaning that there has to be many things changing in order to keep the listener interested and not bored.