Flash Player for Internet Explorer in WIndows 8 & 8.1 is embedded in the browser by Microsoft, and you cannot install it, uninstall it, repair it, or update it from here. There are registry keys and a Windows Update patch that prevent it.
You can only update it via Windows Update.
IE11 which comes with Windows 8.1 is a "rolling train wreck" as far as browsers go. It tops Vista as the worst thing the loons in Redmond, WA have ever unleashed on the computing world. Thinking they were sly, the bozos in development deliberately screwed up the "User-Agent Strings" that allow websites to identify the browser when you visit their site. (IE11's User Agent Strings). Some sites will misidentify it as "Webkit/Gecko" or Mozilla Firefox, while the rest just can't identify it at all. The pages can't recognize the browser, so they don't recognize any of the plugins, like Flash Player, so you're told you need to update it when you already have the latest version. So far, Microsoft has made NO indication that they have any plan to fix it soon, because they're still convinced this is a good thing.
Microsoft's recommendation is to use Compatibility View for affected pages, and "pretend" you're using an different browser. Trouble with that is... it has seen limited success at best, and you have to individually enable it for EVERY page that has problems.
I'm not big on "pretending" so I recommend actually using another browser.
ANY of those will work where IE11 won't, with the Flash Player Plug-in (For all other browsers), and Chrome doesn't even need that because it has its own Flash Player plugin built in.