You will have to press "Z" key to confirm choices, and "X" key to cancel.
Once the game gameplay starts, please press Esc key to open sidebar menu. Select Controls -> Controller Setup
In the Controller Setup menu you will be asked to assign new keys. In game action will be highlighted on screen, and you will have to assign appropriate keyboard key that will fit this action to your needs. For example, when the game highlights "UP" action, you can use UP keyboard key.