Welcome to the Hook Productivity Forum , @jtanzer14 . Thanks for asking.
Our Linkable Mac Apps – Hook page says
GoodTasks – Task Manager with iOS/Mac Reminders & Calendars. Supports linking of Reminders via x-callback-url.
Hook to Newand Calendar events linking not yet supported.
Last time we checked, GoodTask did not have an API to get the ID of calendar events.
According to your screenshot, you seem to have selected a calendar event.