Was looking for a language school in Freiburg DE
I suggest reposting this query in the Germany section of the forum. I'm afraid some of the most knowledgeable folks won't see it here.
If you are looking for a course in German for foreigners, you might check the Goethe Institut. I have no personal experience with them, but they have schools all over including in Freiburg.
I do not have direct experience with German language schools, but would say that Goethe-Institut, while expensive, has the reputation of being quite reliable.
There are many (many) smaller schools in every large-ish city in Germany too, that offer classes mostly to students and immigrants and so on -- I'm sure Freiburg has a range of both small schools and ones connected to larger chains. But you will probably have more luck reading reviews of them that are posted on Google or so, as most people on a travel forum would not have experience with them. These are likely considerably less expensive than Goethe-Institut.