Click Open. If the app that you want to use to open the file type is greyed out, it's because macOS doesn't think there's a valid association between the two.

If you can't change default app by file type in Windows 11/10, then reset the problematic app, remove file type association, etc.

In macOS, the Open With contextual menu that appears when you right-click (or Ctrl-click) on a file provides links to all the applications installed on your Mac that are associated with that file ...