Why Magdeburg? I have a really hard time to find an argument that puts the city in an advantageous position relative to other competitor places (like Dresden, Munich agglomeration, Rhein/Main area, Hamburg agglomeration).
Already prepared grand space for industrial use with energy, water and public transport; 100% carbon neutral wind energy and very soon also water-neutrality were a few of the reasons given.
True, space is a selling point.
Why not? Cheap, Uni Magdeburg is pretty good in STEM, water (yes that is an issue!), close enough to Berlin and Wolfsburg (Volkswagen), good transportation.
Cheap place to build, cheap place to live, cheap labour, pretty good infrastructure. All of the cities you mentioned are very expensive to built in, but also to live in.
If the government pays subsidies they will combine it with strengthening economically weaker areas. No one needs more high quality jobs in the overcrowded and overly expensive Munich area.