The artist's name on the poster is not indicated. By assigning Artist Unknown to a poster it also could mean the artist used a chop mark whereby no signature is seen thus rendering the artist's identity anonymous.
VEB means "Volkseigener Betrieb", a People's Enterprise (i.e., Government owned)
The Socialist Unity Party of Germany or, SED (Sozialistische Einheitspartei Deutschlands), was the ruling party in the East German parliament. The nation of East Germany (Deutsche Demokratische Republik) or DDR, existed from 1949 to 1990.