You must be talking about the web-based DLS? This is in reference to the FTP downloads. If you use the Content Manager in T:ANE or TRS2019, that message doesn't appear.
Yes you can import content from TRS2009. The best way to do this is to use CDPs. Start up TRS2009 Content Manager, and export any routes you want to import into T:ANE.
Import CDP'd routes into T:ANE via Content Manager in that program....
Once installed, check for missing dependencies and download anything that's missing. This will ensure you have the latest assets, and you'll still may have something missing. For those missing, you'll have to export those to CDP in TRS2009 and import those into T:ANE.
The process takes a bit of time, depending upon how much content is involved, and be warned some may need repairs.
This is only an overview of the process - i.e. the top down view. If you need help with any steps, let us know and we can help.
