I have premium TT 2019 also. At the end - after you file your return - there should be a button/option to claim your free version of Quicken, but it is only Quicken Starter. It takes you to the Quicken web page to sign up and it goes through after you put in your credit card (zero fee charged).
I just did this, but it is almost useless unless you get the Quicken Premier version to get investment accounts uploaded. When I try to "upgrade" from the Quicken Starter version, it asks for the full price amount. Not sure how or if we can upgrade from Starter to a higher version and just pay the difference...