In order for your Garmin Smartwatch to be used in conjunction with the WeHunt Garmin app, it must include the following technologies: Compass, ANT+, Bluetooth, Connect IQ and GPS
Here you can search for compatible Garmin watches:
https://apps.garmin.com/en-US/apps/7ec4ab45-9632-4003-8fd5-8d1a411edd38