to use 3 way match vendor bill approval, do we need suite analytics connect?

No. Not sure why you would think you would need that

its showing in the help center. I have configured everything as per help center and suite answers, but still when I tried posting PO receipt and bill with different quantity and price its not showing any pop up message or even the workflow is not initiating on those transactions

You made a copy of the 3 way match workflow and set it to released?

yes