H&R Block uses Flash Player for their onboarding. I've installed it because I've received the Congratulations! You've installed Flash Player. Why can't I find it?

Flash Player is a browser plugin, not a standalone application.

It might help to back up a step and talk about what you're trying to do and what symptoms you're experiencing.  My guess is that you're visiting a site, trying to view a video and that it's telling you that Flash isn't installed.  Since it's up to the remote content to properly detect Flash, there are a couple of reasons for why it might be telling you that Flash isn't installed, even when is.

To give you any useful advice, I'm going to need to know more about your computer and browser:

https://forums.adobe.com/thread/1195540