First tip: Adobe always give a rejection reason, and you need to tell us what it is. For example, IP violation, artefacts, quality issue...
Actually, I do not think it is bad. The focus (depth of field) could be better and the shadows could be 1/2 stop lighter.
Also you should straighten the vertical lines. The post.
This looks like a private storage room. Were you asked for a property release? As you did not show us the refusal reason, and there are no direct recognizable errors, it is difficult for us to give you feed back.
Adding some clarity to enhance the micro-contrasts, and a geometry correction is all I would do.
I would straighten that vertical element and lift the shadows a bit. Otherwise it's well done and an interesting collection of squash.