The game has been released to the public due to lack of development.
Quite literally this was just released one day, not configured for public play.
Check Remember my choice and click in the dialog box above to join experiences faster in the future!
Click RobloxPlayer.exe to run the Roblox installer, which just downloaded via your web browser.
Click Run when prompted by your computer to begin the installation process.
Click Ok once you've successfully installed Roblox.
After installation, click Join below to join the action!