Naturalistically is the adverb: it tells you that something is painted, written, lit, or acted in the naturalistic way — as if you were looking at real life, following the ideas of naturalism. “The room was naturalistically lit” means the light looks like a real window, not a stage spotlight. You do not need this word every day; naturalistic already does most of the work. Use the -ally form when you are describing the manner of the doing, not the thing itself. It is a bookish word. It does not mean “in a natural way” in the everyday sense (that would be naturally).

以自然主義／寫實的方式