Since flash player is no longer available in Safari and Chrome there is no way for mac users to access flash content.
Flash Browser is a new browser focused on supporting flash player. It has a chromium engine so it is fast but it is not meant to be your main browser. Rather it goes along your browser for when you want to access swf content.
Apple users still need a way to play their favorit online games. Flash Browser plants to support this in 2022 and beyond
Here is a quick video on how to install it:
While the source code is freely available on GitHub. This is a beta state product.