2 guesses.
You only specified keyboard input. It is a superflous setting and should be deprecated by Itch. I am assuming here, that your Unity game has all the normal input devices that all other pc games have. Which is mouse and keyboard.
You recreated in Unity what older rpg maker games have: no mouse support to move the character around, and only a crappy non changeable keyboard mapping. Which I would consider incredibly bad design. Even rpg maker games can nowadays be played with mouse, if you activate "touch support".