You should apply for a visa as soon as possible, and not wait for confirmation of enrollment in the study program. The German missions abroad (embassies or consulates) are responsible for this. The "national visa" is intended for longer study stays. You can find more information on the DAAD website.

We strongly encourage you to apply for your visa as early as possible in your home country. While it may be possible to enter Germany on a short-term visa (depending on your country of origin) the visa application process can often take several months to complete. Unfortunately the Geographies of Global Inequalities M.Sc. cannot advise on the specific details of the visa application process. For further information, visit Freie Universität Pass-Service after consulting the proper authorities in your home country.