My husbands employer did not withhold fica the last quarter of 2020 because of Trumps executive order. They are withholding in 2021. How do I record this in turbo tax?

You record only what is listed on his 2020 W-2.

Anything withheld in 2021 goes on the 2021 return that you file in 2022.

turbo tax is calculating that we owe it so I now owe money with our return plus his employer is also deducting it now.  Which means we will have to wait a whole year to get the double payment back.