The iCloud Drive app has never worked properly for me (and others, from what Ive researched). Nothing shows up in it. However, this Documents app is a terrific substitute. Easy to create folders, easy to move & copy items, easy to rename files, everything!! This is what Apples app should have done, shame on them!
The iBooks app has also been a horror for me. Disappearing books & pdfs, sync problems, renaming pdfs in iBooks only works in iBooks - the original name is retained outside of the app, crappy iBooks folder organization. The Readdle Documents app fixes all this and is a great substitute for iBooks. Shame on Apple for the iBooks crude & confusing setup!!
Steve Rogers 1978ii about Documents: File Manager & Docs, v5.5.5