As I understand it, those in the line of the Levites were too many for them all to serve in the Temple all of the time year round. For this reason they would be given service duties year by year. Zachariah would have been among the sons of Aaron in that he was in the Holy Place to burn incense, but the Ark was in the Most Holy Place and that was not where he was, so I don’t think would have been Yom Kippur.
I am doing this from memory so if the details are fuzzy I welcome edition
God Bless