@bmontonera
IF you used the "FREE" version in a prior year, then you must upgrade...and PAY for PLUS (or higher version) in the exact-same UserID account that you used in the prior year you are attempting to print now.
IF you switched accounts between the years (should not do that unless you divorce, separated, or get married between tax filings.....or start doing MFS tax returns)....then you must have a paid-for 2018 tax account (PLUS or higher), and then you have to call Customer Support to get the other account unlocked:
https://ttlc.intuit.com/community/using-turbotax/help/what-is-the-turbotax-phone-number/00/25632
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
