。
She got to the hotel late at night.
Literal
She [topic-は] hotel [at-に] night late arrived.
夜遅く ('late at night') is a fixed adverbial phrase with no particle — Japanese's compact way to express temporal qualification. 着く takes に for the destination — point of arrival rather than direction. The plain past 着いた reads as a simple factual narrative event. Notice that Japanese stacks two adverbial elements (に for hotel, then 夜遅く as a temporal modifier) directly before the verb without intervening conjunctions.