Can see files on SD card in Lightning to USB 3 Camera Adapter – USB Flash Drive Pro Version Review

Not sure what this app does re USB. I have an Apple USB 3 camera adapter. When I plug in an SD card I can use Apple Photos to import photos. I wanted to use this app to browse the SD card’s FAT file system to see what else besides photos were on it before I reformatted it. This app can’t do it it. It can’t browse files local to the iPad Mini 3 either. When I go to “Files: Files stored locally” there are no files or files visible. What does this app do?
Review by c of c, p of wp on USB Flash Drive Pro Version.