Butter Bot
Any standard USB-C charger will do — the same kind you already use for most phones and laptops. Just plug it in; there's no special adapter to hunt down.
The controller
The controller's batteries aren't rechargeable — but you can plug the controller into USB-C and run it straight from that instead, using the cable as its power source.
So it's the same USB-C cable whether you're topping up Butter Bot or powering the controller.