You cannot print your tax return or the extension until the TurboTax account fees are paid.  Your message shows that you are using the TurboTax Live Basic edition which includes Live CPA support.  It is NOT the Free edition.
Clear your tax return and start over with the Free edition.  Complete the tax return using the Free Edition and register the Free Edition.  Then you can print your tax return to include the Form 4868 Extension request.

If you have not paid for the online edition you are using, have not filed your tax return or registered the Free edition, then you can clear your return and start over with a lower priced edition.  Click on Tax Tools on the left side of the program screen while working on the 2018 online tax return.  Click on Clear & Start Over.

Thank you

Ok ... I am confused ... if you do not need to file since you have no taxable income then WHY did you file a useless extension ?   And why would a mortgage company want it ?  Something is very wrong here.

and why would you need TT Live?

@Critter#2  Based on OP's screen name, I suspect income is LT Capital Gains taxed at 0%.  But lender still needs proof of income.

If they had stock sales they most certainly need to file a return EVEN if they owe nothing. Now the original question is making more sense.

The extension form thru TT would look like this one from the IRS and it would not say it was filed anyway ... you can fill it in and print it and give it to those fools.  https://www.irs.gov/pub/irs-pdf/f4868.pdf

What you really want is the filing history showing an extension was filed and accepted ... of course it will not say what was on the form only that one was filed.   If you really want proof it was filed you should get an account transcript from the IRS.    https://www.irs.gov/individuals/tax-return-transcript-types-and-ways-to-order-them

Your return's electronic filing status history records all e-filing activity related to the return, including the Electronic Postmark. You can print it out if needed. 

TurboTax Online

https://shop.turbotax.intuit.com/efile/efile_status_lookup.jsp  -- enter the Social Security number of the first taxpayer on the return and the ZIP code to retrieve your filing status history.

TurboTax CD/Download software

(Windows) From the TurboTax File menu, select Electronic Filing > Show Electronic Filing Status History.
(Mac) From the TurboTax File menu, select Check E-Filing Status.

Link to form was in my original answer after the word "fools"  😉