This has been a known issue with TurboTax this year. See the information I'm linking below to take care of this issue and get your return filed.
Why am I being asked for my email before I can checkout?
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***