Doesn't the message tell you why you have to upgrade?
Is the total of box 4 on your two W-2s more than $9,932.40? That would require Schedule 3, which is not included in Free Edition.
Is box 5 on either W-2 more than $200,000, or is the total of box 5 on your two W-2s more than $250,000 if you are married filing jointly, $125,000 for married filing separately, or $200,000 for any other filing status? If so, you have to file Form 8959, which is not included in Free Edition.
Is there an amount in box 10 of either W-2? That would require filing Form 2441, which is not included in Free Edition.
What do you have in boxes 12 and 14 of your W-2s? There are a number of possible entries in one of those boxes that could require upgrading.