You are able to begin your tax return using TurboTax Free, but if you do not qualify for TurboTax Free, you will be prompted to upgrade.
Please see the following link for tax situations covered in TurboTax Free Edition.
If you don't qualify for TurboTax Free Edition and you haven't yet filed your tax return, you may qualify for TurboTax Free File Program.
Here is more information on TurboTax Free File Program.
You can follow the instructions in the following FAQ to switch to the Free File Program.
Please follow the instructions listed in the following TurboTax FAQ to contact Customer Support if you need further assistance. https://ttlc.intuit.com/replies/3300041