このバスの会社によると、東京では1週間に3日、昼と夜の2回ずつ走る予定で、予約が必要です。
According to the company that runs these buses, they plan to run the Tokyo bus three times a week, twice each in the afternoon and evening. A reservation will be needed.
I'm unsure of how to understand 昼と夜の2回ずつ. Does this mean twice in the afternoon and twice in the evening, or does it mean once in the afternoon and once in the evening (making two times in total)?
I'm not even sure whether ずつ modifies 2回 or 3日.
Whichever is the correct interpretation how would you adjust it to give the other one?