If you did not use the TurobTax online editions for tax year 2018 or you only used the Free online edition then the requirement is that you start a 2019 tax return, upgrade and pay for the Plus edition and then you should be able to access the prior year return and download the tax data file.
Since you are having this difficulty in registering, it would be best for you to contact TurboTax support for assistance with this problem. And Yes I agree it should be easier than this just to get the tax data file.
Use this website to contact TurboTax support during business hours - https://support.turbotax.intuit.com/contact/
Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax
