Does anyone know how to begin filing taxes for free? I thought payment is when we actually file. Every time I select the option it sends me back to the $80 option, nope!

I select the DIY option and select my preferences when it starts at $0 then I get asked about how I filed last year. After that it pulls up the Deluxe option and higher. Why do I have to pay immediately instead of it coming out of the return?