Tap Files icon to open it.
You can view the storage usage here. Tap SD card to view all files on your SD card, or explore files by the type (Photos/Music/Videos/Docs). Received includes all files you received from AirDroid. Large Files lists files over 10 MB.
Tap the folder/file to open. Select one or more files/folders to do more actions (delete/copy/cut/select all).
You can also long-press the file/folder to do these actions.
When browsing, tap the overflow icon to sort files, create new folder, show hidden files and refresh.