The advertised movie Kampf um Deutschland is an East German documentary about the fight of communists against fascism between 1930 and 1945 and building a communist Germany after 1945.
The movie directed by Joachim Hellwig and had premiere on October 7, 1963 - the 14th annivarsary of the establishment of the German Democratic Republic. The premiere night was not in this cinema (it was still a building site), it was in Filmtheater Kosmos in Berlin.
I don't know when this documentary was shown in Kino International, maybe in spring 1964. The postcard is from 1964. It is a good view of the cinema and its unique architecture.