No, decks can be created and edited within AnkiApp directly on your mobile device—no computer or desktop app required.
However, you may find it more efficient to create and edit flashcards on a desktop computer. The AnkiApp web client is available at: http://web.ankiapp.com. AnkiApp is also available as a native app on Windows (Download from Windows Store) and Mac OSX 10.9+ (Download from Mac App Store). The web/desktop apps work seamlessly with AnkiApp on mobile devices.