Did you start before Oct 15? You need to switch to the Desktop program to finish.
Online is now closed. You have to print it out and mail it now. Or finish it and mail.
How to finish a prior year online return
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
If you paid for the Online version you can ask support to give you the Desktop download. Contact Customer Service 5am-5pm Pacific M-F
https://support.turbotax.intuit.com/contact/
