I was given an iPad and I can’t unlock it

Your description suggests that the donor has not signed the device out of their iCloud account and that the activation lock is still active.

Read How to remove Activation Lock - Apple Support to see how they can fix this for you. The page is also linked above. You may have viewed this page before posting your question.

What they should have done before passing the iPad to you is follow all the steps in What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support