Pairing your Mac with an Apple Watch unlocks a feature that saves you a lot of time. With your Apple Watch, you can unlock your Mac without having to type in your password. Your Mac automatically recognizes your Apple Watch and does the unlocking for you.
This feature gives you instant access to your Mac when you're wearing your Apple Watch. Just wake up your Mac and you’re ready to go – without typing a password.
The first time you log in after you turn on, restart, or log out of your Mac, you must log in by entering your password manually. After that, Apple Watch logs in for you.
How to set up Auto Unlock
1) Make sure that your Mac and Apple Watch meet the system requirements for Auto Unlock.
2) Make sure that your devices are set up as follows:
Your Mac has Wi-Fi and Bluetooth turned on.
Your Mac and Apple Watch are signed in to iCloud with the same Apple ID, and your Apple ID is using two-factor authentication.
Your Apple Watch is using a passcode.
3) Choose Apple menu > System Preferences, then click Security & Privacy. Select ”Use your Apple Watch to unlock apps and your Mac” or ”Allow your Apple Watch to unlock your Mac.”