I am a subscriber and want to watch Sling TV on my desktop Windows 10 PC using Firefox 62.0b10 (64-bit). I open the Sling.com website, sign in and see a big blue button that says "Watch Now". When I press it I am taken to a Microsoft.com page ( https://www.microsoft.com/en-us/p/sling-tv/9nblggh4x7wp?rtc=1&activetab=pivot%3aoverviewtab ) that is devoted to Sling TV. I then press the big blue "Get" button and get a Firefox.exe pop-up window with the following text: "This file does not have an app associated with it for performing this action. Please install an app or, if one is already installed, create an association in the Default Apps Settings page." I am totally UN-technical. What am I missing here? Does Firefox need an app? If so, which one? Where do I get it? I just want to watch Sling on my PC. See attached .jpg file