I think (!) that all your previous files will be available as downloads but in answer to a query of mine, the download manager works by activation number so you need to go through all your installations, enter the activation number and then the download manager finds the files you bought with that year's package.
All the download manager will find is the files associated with the 2019 purchase and subsequent activation number.
I asked because I bought the complete set of RealTracks (as then was) with the 2018 package and was told that if I did a reinstall I would have to install 2018 first, download my files and then install and activate 2019 to get the latest.
It would be easier if we all had a profile with our purchases but that is obviously more complicated than numbers assigned automatically.
So I thought this would be the case, but I have two problems with this.
1. The download manager was not a feature yet in BiaB 2015, so even though I downloaded and activated that version first, I could not install RTs via the install manager.
2. I tried to activate 2016, and 2017, but when I launched the activation utility, a notification popped up saying that it was already activated...
Thanks for taking the time to respond, tho.