how can pair my smart watch serie 3 that was own by sister before having problem she already unlocked in her side i have her email and password to activated
Apple Watch Series 3
Please see the steps your sister should have followed to make the watch ready, described in Apple's support document
In particular, the watch needs to be removed from her Apple ID so you can set it up correctly with your Apple ID on your iPhone. If you don't do this you will be blocked by Activation Lock. About Activation Lock on your Apple Watch - Apple Support
When your sister's Activation Lock has been cleared and the watch has been erased back to factory condition, you should be ready to begin pairing and setup to your iPhone and your Apple ID.
Set up your Apple Watch - Apple Support
Please see the steps your sister should have followed to make the watch ready, described in Apple's support document
In particular, the watch needs to be removed from her Apple ID so you can set it up correctly with your Apple ID on your iPhone. If you don't do this you will be blocked by Activation Lock. About Activation Lock on your Apple Watch - Apple Support
When your sister's Activation Lock has been cleared and the watch has been erased back to factory condition, you should be ready to begin pairing and setup to your iPhone and your Apple ID.
Set up your Apple Watch - Apple Support
my sister gave me her smart watchserie3 because she got a new one but iam having a hard time to pairing with my i phone pro max14
