Translation:It takes six months to develop this.
Yes. Actually, there's a third alternative as well - you could say just Det tar sex månader att utveckla. In this case, it's because you're syaing "That takes six months to develop", which while syntactically different conveys the same semantic information.
Note also that there's a slight difference between det and det där, but I can't quite put my finger on it. The latter is used more like "that, that thing, that thing over there", so in general I advise you to use only det unless you're pointing at something.