Your Wi-Fi is on and connected - If you need to configure your Wi-Fi settings on your Mac for whatever reason, you can do so within the Network section of System Preferences. You can turn on the feature from within the Bluetooth section of System Preferences. Your Bluetooth is turned on - This isn’t a problem for the Apple Watch, but make sure Bluetooth is enabled on your Mac - sometimes Bluetooth ends up disabled, especially if you’ve had past trouble with accessories. Check and double-check this list before you move on. Your next job is to check your settings and make sure that everything is set up so that your Apple Watch and Mac can talk to one another, even when your Mac is just waking up. You can click on your Mac Notification sidebar to catch a look at any outstanding updates that have yet to be applied, just in case. If you have a Mac that has the right hardware capabilities, it also needs to be running MacOS Sierra 10.12 or later.
You need a mid-2013 model or newer to use this feature, so older Macs simply don’t qualify. The requirements for your Mac are a little more demanding. Then, access the My Watch app and download any available software updates. Just put the Apple Watch on its charger, make sure your iPhone is connected to a reliable Wi-Fi network, and place your phone and Watch beside one another.
If you’ve never tried to update your Apple Watch before, it’s easy to do so. On the smartwatch side, you will need to be using WatchOS 3 or later.
The Auto Unlock feature does have some system requirements, which mostly involve newer operating system updates.