I am used to having easy access to the file manager on my phone (LG G4). So I was surprised to not be able to locate it on my Nexus 9. I found how to locate the files here -> http://http://www.techtimes.com/articles/94044/20151012/android-6-0-marshmallow-has-a-built-in-file-manager-heres-how-to-access-it.htm
Simply go to Settings -> Storage & USB -> Explore. Now you will see your files. The article goes on to state that a third party app will be needed to have access to more functions to manage and share files.
Simply go to Settings -> Storage & USB -> Explore. Now you will see your files. The article goes on to state that a third party app will be needed to have access to more functions to manage and share files.