It's not left that causes the possible ambiguity. You could replace it with gave, wrote, delivered, or any number of other verbs.
Also, depending on the interpretation of the word, directions may or may not cause ambiguity.
In the following sense, following directions would not result in ambiguity, at least not practically speaking:
3 b : assistance in pointing out the proper route —usually used in plural
// asked for directions to the beach
In other words, the directions given might be:
Go to the end of the driveway and turn left, go five miles, turn right, go through the stop light, and then look for the sign that says "Pine Ridge Hotel."
In this sense, the end result is the same. Whether the reader follows the person or follows a set of directions themselves, they will still end up at the hotel.
On the other hand, it could be ambiguous in the way pointed out if the other sense of directions is meant:
3 a : an explicit instruction : ORDER
// carefully read the directions
// follow directions
This type of direction might not say anything about a travel path or destination at all:
Mix the ingredients thoroughly, and then put them into an oven preheated to 350° for 45 minutes.
In this interpretation, if the reader follows the person, something entirely different will occur than if they follow a set of directions themselves. Either they'll end up at the hotel, or they'll end up with a cake.
Speaking entirely personally, I'm always careful to distinguish between directions and instructions. When I use the word directions, I use it in the unambiguous sense. But I recognize that's not true of everyone.
I suppose you could say that the sentence itself is ambiguous—even if, in one sense of the word, the result is not. Also, it's certainly the case that the sentence itself doesn't convey the intended sense of the word.