If TrackIR does not work in theHunter (but works in other applications) you need to update TrackIR.
Make sure your internet connection is working. Then start TrackIR and click on the Game Updates button (click on Update, not Dismiss).
If this button is missing, select Check For Game Updates... in the menu.
Once updated, start theHunter and select Options in the main menu. Under Mouse/Keyboard, make sure TrackIR is set to Enabled.