That’s a very generic error that it cannot load. That can be from missing Component file in the Plug-Ins/Components folder or that you didn’t refresh when the plugin first time appeared (reboot or call
killall -9 AudioComponentRegistrar
Or you didn’t build the AU target, or the wrong Architecture…
Its at the bottom of the plist, a triangle on the left lets you expand it. Maybe it’d be better to post the raw .plist contents instead of a screenshot of the editor, though …