You do not say what years you are trying to install/download. TT no longer supports or provides updates for software older than 2021 so you will not be able to do anything with 2020 or earlier.
HOW DO I GET STARTED WITH TT DESKTOP
Why do you need to install them? How far back? Do you have backups of the pdf files and data files ending in .taxyyyy?
The last couple of years you have to log into an Intuit Account when you install even from the CD, so your downloads and licenses are listed there (even if you bought it from somewhere else) so if you need to download to install it again or install on another computer, even on the other operating system (Windows, Mac). And the download will always be up to date with all the updates.
If you have a License Code you should be able to download 2021-2023 here on the prior program page. Click on the little blue “access it here” link at the end of the top paragraph.
TurboTax® 2023 Prior Year Tax Prep - File Past Years' Taxes
For prior years……
Sorry you will never be able to activate the 2019 program with the License Code. The License Code started in 2019. So 2019 needs to connect to Turbo Tax to verify the License Code. But they have stopped supporting 2019.
You can try to install2018 or prior but you won't be able to update or download any state program you will need.