Ukrainian Keyboard - Ukrainian Input Keyboard

I am studying Ukrainian through the Duolingo app on my iPad and in order to answer many of the questions in the lesson, you need to use the Cyrillic keyboard. ONLY ONCE has this worked for me. The keyboard will not appear on the monitor. The settings for this app are useless. I even made a schematic of what Cyrillic letters are associated with our English letters, which enabled me to type on my own external iPad keyboard ONCE. Maybe I’m doing something very wrong!??