cjrgreen: As near as I have been able to determine, these files are part of a closed beta. I asked a CDPR admin and was told they would not comment on an unannounced product. So unless you're an invited beta tester, the files are none of your business.
Clearly a mistake on their part as I was initially able to download TW2 from the Steam Linux client, and it showed as a supported Linux game. That being said it has since been removed from the Linux roster on Steam, so it looks like it's going to a bit longer before we can play it (on Linux that is)