"It took two weeks."
FYI: I checked what 間 is, since it was not taught in this course yet. It means ‘(time) period, interval’, so 二週間 means ”two weeks(' period)”, and it's pronounced [ni shuu kan].
I believe that kanji is introduced in Position 1 (as of this time of writing). 間 means 'period' or 'space', in a temporal or spatial context
Wait, what the heck? Why are we using 間 with weeks, but not with days? In both cases, we're talking about a span of time, so I don't see why 間 isn't used with both.
I think that very good lessons of japanese are George Trumbley's "Japanese from zero" series and their video version on youtube
間 indeed means a period of time. It's used a lot, and is a counter for periods of time. What's interesting is that it's used in this question, but then many questions in the time module omit 間 making it confusing for new learners of Japanese.
How long does it take? = どのぐらいかかりますか？
It takes two weeks = 二週間かかります
two years 二年間かかります
two days 二日間かかります