How do I turn on Adobe Flash permanently in Microsoft Edge preview builds?
You can only turn on Adobe Flash Player for a particular website – not for all sites permanently. This is because Adobe announced that Flash would no longer be supported after 2020. Microsoft has been phasing it out and plans to remove Flash from Windows entirely by the end of 2020. Other browsers like Google, Mozilla, and Safari are also phasing Adobe Flash in the same timeframe.
Content Update: 4/22/2019