I was having the same problem with that message, and this one too: "roblox continues installation without flag settings from https://clientsettingscdn.toblox.com/v2/settings/application/PCClientBootstrapper ".
The solution was to rename the Roblox's folder in %appdata% - Local- (it was there although I had uninstalled it before. I didn't want to lose what it contained just in case) when trying to install it again, it created a new Roblox's folder, and it installed correctly 🙌