Is your iPad an M series iPad? If it isn’t that may be why you need a powered hub. Mine which is an M1 iPad Pro doesn’t need a powered hub.I have a Belkin hub with PD in and it copied 50 or so Z8/9 files at 60ish MB each in just a minute or so although I didn’t time it. I also have the same hub discussed above but don’t use it as the iPad needs a powered hub to support both the card reader and SSD at the same time.