this is one of those games that is so old that the movement mapping was set to the analog stick with no way to set it to digital d-pad input (at the same time d-pad was usually mapped to the analog movement input on controller back when the game was released so it's a case of it being a product of it's time)

and the amount of buttons used are the exact same as the sega mega drive version (meaning 3 buttons and a start button though i don't remember if the pc version maps the start button to something on the controller)

you're better off using a keyboard to controller input program (or whatever it's called) for this game