It’s needless to say that the last sharing section which is the most meaningful is donation, during which time everyone present, teachers or students, is expected to donate one or more books to the library. 

【翻译】不用说，最后一个最有意义的共享部分是捐赠，在此期间，在场的每个人，无论是老师还是学生，都应该向图书馆捐赠一本或更多的书。

1. 第一个which 使用有误，应改为that，因为先行词含有the last 唯一概念。

2. 第二个which 作定语，修饰time，指代the last sharing section 这段时间。又如：

It took two years for me to get better, during which time he spoon-fed me and did absolutely everything around the house.  （指代整个主句这段时间，实际是两年）

我过了两年时间才好起来，其间他喂我进食，并承担全部的家务。

来自柯林斯例句

Half an hour passed, during which time the ark had been slowly stealing over the water.  （指代整个主句产生的时间，实际指半个小时）

半小时过去了, 这时船在湖面上无声无息地缓缓滑行。

来自辞典例句