iCloud drive is not functional yet. When it asked if you wanted to set up iCloud drive, You should of said no or select skip for now (can't remember what option it had. In settings, you should be able to disable iCloud drive for now. Once Apple opens up the doors to iCloud Drive, enable it.
Unfortunately, I don't think you can go back to regular iCloud (iCloud before IOS 8) for your documents, etc. I may be wrong though.