I was going by what it said on the site you've found so that earns you the point.
However, Wendax is probably right in that it's based on a pre-war BMW, as it's unlikely a GDR citizen would have converted a car so new into a special in the early 1950s, so whilst I was looking for EMW 340 as PJ has posted it's most probably not right.
If I give Wendax and PJ a point each that's probably fairest, but a definitive identification is still not definitely positive!