how to enable auto unlock on your mac and apple watch

you'll need to make sure your Mac and Apple Watch are compatible, and that you've set up authentication for your iCloud account..   1, or 2, you'll need to be running watchOS 3 or later on your smartwatch additionally, your Mac needs to be running macOS Sierra or later..   that requirement changes Because of W2 chip, you'll need to be running watchOS 4 on your wearable, and macOS High Sierra on your Mac.   Apple wants to make sure your computer is as safe as can be by enabling authentication on your iCloud account..   In order to authentication, your iPhone will also need to be running iOS 9 or higher..   In order to use Auto Unlock, your Apple Watch and Mac must be using iCloud account.   You may not have thought it necessary to use passcode with your Apple Watch when you first set it up, except if you want to use Auto Unlock, you'll need one..   your Mac will register the device and allow you to turn on Auto Unlock...   Tick the box to Allow your Apple Watch to unlock your Mac..   Note If you do not see the box to allow your Apple Watch to unlock your Mac, there's issue.   Read more