There are 2 parts to tax returns in the US: the Federal File and the State File (though, not all states require you to file taxes). With FreeTaxUSA The Federal File is always free. The State File is $15 unless you make under a certain amount and use the IRS link to get to the website.
This IRS link issue is something I've noticed with TurboTax and TaxSlayer in the past. They hide their free file (even the Federal File) from users unless they use the IRS link.