"Vous êtes blessé et il vous faut un médecin."
Translation:You are hurt and you need a doctor.
It is the difference between the impersonal "a doctor is needed" and the personal "you need a doctor". Both make sense, but omitting the second "vous" changes the meaning.
I think they meant in English "you are hurt and need a doctor" is the same as "you are hurt and you need a doctor" the former got marked incorrect.
All the possible variations of blessé are accepted if the rest of the sentence is correct.
In the dictation, I wrote "Vous êtes blessée et il vous faut un médecin". It accepted it, but "corrected" the feminine "blessée" to the masculine "blessé". This is wrong. They sound the same and both are valid transcriptions, lacking any context that would require one or the other.
Why is the plural (blesses) not accepted? "Vous" is ambiguous and there could be two people injured.