I am a student from outside the European Union currently starting my Master's in Tallinn, Estonia. I have lived here for 3 years already as I completed my bachelor's, naturally, I have a residence permit and visa, which is valid until 2022.
I want to do an internship in Germany and I am trying to find out how to go there.
I have tried to research this everywhere but every single source about non-EU citizens working/interning in Germany is all about people that are coming from a country outside the EU. There is almost zero information about the procedure of someone who is not an EU citizen but resides in the EU, with a residence permit, visa, and free allowance to travel to all EU members for up to 90 days (internship offer I received is for 90 days). I am applying for the ZAV approval to work in Germany, but everywhere I look I supposedly need this special "internship visa", but it seems to me that this visa only matters to those who come directly from countries outside the EU and need this internship visa in order to enter the EU, which is not the case as I am already in the EU, but I cannot confirm this information anywhere to my future employer who is concerned about it and they also cannot find any information either, they want the assurance that nothing will go wrong if I just get the ZAV approval and hop on the next plane.
And yes, I tried contacting the embassy in Tallinn but they have been incredibly unhelpful and contradicting so I wanted to ask anyone who has had this experience or knows about it.