An "appie" is short for Apprentice PH. In Zim, and I'm sure elsewhere, a guy that wants to be a PH has to put in a few years as an "apprentice" PH before he can become a full fledged PH and hunt on his own without further supervision. An apprentice has to get his experience and learn how to hunt, how to handle different situations, and how to work with the client, so usually goes along as an extra hand with the PH and trackers while hunting. In this case, the appie was obviously in the wrong place at the wrong time.
