I’m due at a meeting then,

1楼解释不正确
due at 不是一个词组,这里at a meeting是一个词组
due 有这么几个意思
1,应付的
The rent is due (= should be paid) at the end of the month.
房租应该在每月末付
2,预期的,预计的,要发生的
Their first baby is due in January.
他们第一个孩子一月份出生(预产期一月)
3,due to = because of 因为
在题目中这里是第二种含义,原句是这样的
M:Professor Atkinson,can I see you after this class?
W:I’m due at a meeting then-how about the same time on Friday
我那时要去一个会议.
提问时要加上下文,以便于准确翻译