"Please stop at the corner."
止まる is intransitive, so we do not care what to stop. If we use 止める (transitive) then there should be an object, for example 車（くるま）, and we will switch the focus to stop "something," while we don't really care in most cases. In this question though i think both are correct translation.
止める would work if you're talking about someone driving, because in that case you're stopping the car, but if you're talking about someone walking, it wouldn't work, would it? Because you're not actually stopping something. You're the one stopping? (Obviously either way should work here, since there's no context to indicate whether you're talking to someone driving or walking)