Translation:The child is walking with a man and a woman.
IMO as a native English speaker it's not necessary since "the" before "man" covers both. I reported it and would encourage you to do the same.
I'm a native speaker too and I say that, depending on the situation (which isn't specified here), you can have "the" before both the "man" and the "woman."
I confess, I'm a bit confused. The word for man, above, appears to have a feminine Instrumental case ending. Is it possible that the word for "man" in Russian is of the feminine gender? I'd appreciate an answer from someone more knowledgeable than me.