My Apple Watch is not connecting to my iPhone

Your dad has to follow all the steps in this link to remove that activation lock;

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

Request an Online Activation Lock Removal here.

Or this;

If you can't remember/gain access to the apple id that paired the watch to the phone.Take the watch and it's receipt along with some photo id and any other proof of ownership to an Apple Store and request that they remove the Activation Lock for you.

Otherwise the watch will be of no use to you.

Did you just buy this watch from somebody?.