To complete and file a 2018 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2018 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/

A 2018 tax return can only be printed and mailed, it cannot be e-filed.

The TurobTax Premier edition is recommended for stock stales but is not required when using the desktop editions.  All the desktop editions include the same forms, schedules and worksheets.

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

How to enter a summary in lieu of individual transactions

Your brokerage statements should include a summary of your transactions, grouped by sales category, for example "Box A short-term covered" or "Box D long-term covered". You'll enter the summary info instead of each individual transaction.

1. Open your return in TurboTax Online (if it's not already open) and search for stock sales in the upper-right corner.
2. Click or tap the "Jump to" link in the search results.
3. Answer Yes to both Did you sell any investments? and Did you get a 1099-B?
   • If you land on Here's the investment sales info we have so far, select Add More Sales. Then answer Yes to Did you get a 1099-B?
4. On the Choose Your Bank or Brokerage import screen, select I'll type it in myself.
5. Select or enter your brokerage on the next screen and continue.
6. On the following screen (Tell us about...) select the second option, I'll enter a summary.
7. On the same screen, enter the total proceeds (sales) and cost basis, along with the sales category. Refer to your 1099-B for the amounts and category. When finished, select Done.
8. Follow the onscreen instructions to enter additional sales or to view a summary.

When you are done entering all your sales transactions, you'll eventually come to the Here's the investment sales info we have so far screen. Here you can edit, delete, or enter more sales.

As an active investor, be aware that your category Box A sales without adjustments do not require Form 8949, so there is no reason to import or key in those transactions.

IRS requires details to be listed on Form 8949,
or on your own forms (e.g. consolidated 1099-B) which have the same information and in the same manner as Form 8949.
Either way, if you choose to summarize, you have to mail the transaction details to the IRS within three business days of IRS accepting your e-Filed tax return.(unless you have attached a PDF of the transactions details to your e-Filed return. TurboTax does not offer this feature).
Exception: if you summarize Category A or Category D, Form 8949 is not needed for transactions without adjustments. No mailing is necessary.