trying to connect Garmin to my apple mac

Since that watch is not an Apple product, you will have to contact Garmin customer service for help. It is up to third party devices and apps to make them compatible with Apple products. I found this link which may be helpful.

https://support.garmin.com/en-US/

If I recall correctly, connecting a Garmin device requires Garmin software. The link that Carol B. provided should get you started.