Apple watch not connecting to iphone

You may have been scammed by someone who didn't own that watch!

You are describing Activation Lock (AL). AL prevents lost or stolen watches from being used by other people. Only the original owner, the person whose Apple ID you see, can remove the AL. Otherwise, you cannot use this watch.

The original owner should have followed these instructions before selling the watch;

Before you sell your  Watch... -

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

M1 Mac mini, macOS 13.4;  Watch, series 7 GPS/cellular, watchOS 9.5; iPad Pro 2nd Gen, iPadOS 16.5; iPhone 12 Pro, iOS 16.5; TV 4th Gen, tvOS 16.5; HomePods, audioOS 16.5 and Airport Express w/ Airplay 2

According to the watch, she hasn't.

Give her the link of what she needs to do before giving it to you so she can see if she followed the instructions exactly.