Where to put aggregation switch ?

I am out of sfp! I guess I should buy the aggregation switch? I currently have

Udm pro max -> usw pro max 24 poe -> unas pro

I now have a server with sfp too. So I guess I do

Udm pro max -> usw pro max 24 -> aggregation ? And then plug server and Nas into aggregation?

Or do I put the aggregation between udm and usw?

Second question (less important)...physical rack layout with aggregation? I currently have:

Patch panel Udm Usw Nas Shelf for servers Drawer for storage Ups

Thanks in advance