Hey giselle! Sorry, I don't have any information specific to Argentina nor DAAD. Still I had to come back from Mexico to Italy in mid March and that was still possible even though airports were partially closed in Italy. What I have learnt through my specific experience is that flights are operating if you have a reason outside of tourism to go to another country and you will be boarded on flights that are bringing expats home. They are more expensive than usual and you will have to do more layovers. My best advice would be to contact your embassy and ask if study purposes would be a valid reason to travel and then ask DAAD for the documents you would need to prove it (e.g. extended stay visa, an address of residency where you can self isolate upon arrival before starting the activities etc.)
Sorry if the answer is unrelated! Best of luck x