First if it did not go thru it is now too late to file an extension ... and when the extension was accepted or rejected you should have gotten an email from TT ... Use this TurboTax website to check the status of an e-filed form and if it was either accepted or rejected -https://turbotax.intuit.com/tax-tools/efile-status-lookup/
To print the Form 4868 extension request you have to be working from within the 2018 online account, not just signed onto the account.
After you file:
When you sign onto your 2018 online account and are on the screen that states Welcome Home, click on Taxes at the top of the online program screen. Then when you are on the 2018 Timeline, under Some things you can do: click on Add a state (you will not actually be adding a state). This will take you into the 2018 online tax return.
Before you file:
Or when you sign onto your 2018 online account and are on the 2018 Timeline screen, click on the large Orange Continue My Return button to take you into the 2018 online tax return.
You have to pay the TurboTax account fees before you can print any of the forms, schedules and worksheets that are included in the tax return.
To pay the TurboTax online account fees by credit card, without completing the 2018 return at this time, click on My Account at the top of the online program screen. Then click on Print Center. Then click on Print, save or preview this year's return. On the next page, to pay by credit card, click Continue. On the next screen it will ask if you want Audit Defense, if you do not want this option just click on the Continue button. The next screen will ask for all your credit card information so you can pay for the account.
To print the form:
If you have already paid the TurboTax account fees and are working within the 2018 tax return, click on My Account at the top of the online program screen. Then click on Print Center. Then click on Print, save or preview this year's return. On the TurboTax Print Center window, select from the dropdown Forms filed with the government plus all worksheets. Choose the option on how you want to print or save.
Once the PDF has been downloaded to your computer, you can view or print the return with any PDF compatible viewer, such as Adobe Reader.