Why do you "need" a controller? You could probably make something work with JoyToKey, but there are still parts of the game where you need to type messages. You're talking about a game that was released back when the NES was new.

No you don't. Unless you are playing a console version, you want to use the keyboard and there is no context you NEED a controller.

The PC version of Ultima IV was built for the keyboard and makes use of a wide range of keys to interact with the game. So I don't think there is a way to run it with a controller.

You could try this handheld keyboard: https://www.amazon.com/dp/B07C3W6M97/?coliid=I1U8EK006UDJMI&colid=3OB4CE31V3HJ2&psc=1&ref_=lv_ov_lig_dp_it