Because the Education Credits tax form is no longer supported in the Free edition.
With the new tax law reform, Tax Cut and Job Acts TCJA, you might need to use new tax forms to claim the same deductions, credits, or forms of income. Some of the situations have been transformed into TurboTax Deluxe and TurboTax Live Deluxe, instead of in Free Edition. For more information, click here: Deluxe edition