A Microsoft file hosting and synchronization service.
Great idea however when I did that this morning after reading still had to rotate the ipad even in the files app and it crashed when in landscape. Only when I signed in on portrait mode did it work. And after that I was able to use it so far and it is a great workaround. Just remember when in the files app to sign in in portrait or play with it at first and now it seems fine accessing onedrive in the files app.