Unfortunately, as of January 1st, 2021 Adobe is no longer supporting Adobe flash player. Adobe also states that they will block Flash content from running all together beginning January 12, 2021. A beloved piece of the Internet history is about to die forever.
Im hopping that at some point that flash is forked or somehow implemented into html5. At very least I would hope standalone flash players stay around.
It looks like you may be able to play some of the flashes in the browser there. Also, here is the standalone player for windows. If you run Linux search your package manager flashplayer-standalone or something along those lines.
As a humble tribute to Adobe flash, I have put together a little collection of my favorite flash games and animations here on this page.
I'm sure there are some more flashes I have forgotten about. This page will likely see more updates at some point. I still have lots of my personal archives to go through.