Adding back a deleted account

Changed password on a gmail account and it works on all my devices/Webmail but not in up-to-date MacBook Mail. I deleted the acct in Mail to try to re-add in "accounts" but Mail won't let me add the acct back in without "authenticating in Safari " but nothing happens when I click "open Safari." I have logged in at the account webmail and can send and receive there with no problem. But want it back in desktop Mail.