He was told NO SUCH THING. The dispatcher said we don’t need you to do that, quite different then saying don’t do that.
Sorry but to me that means "quit following the guy."
Zimmerman had no authority to confront anyone IMO. Even if he was witnessing a theft, his job was to call the police, observe license numbers, descriptions etc but never to intentionally confront. He had no training for anything like that. And that is essentially why he is sitting where he is today. And unfortunately, a young guy is dead.