Flash Player installer will be downloaded and saved to your default 'save to' location.In step 2 select which browser you wish to install Flash Player for.To install Flash Player on OS X 10.8, do the following: With that said, while OS X 10.8.5 is no longer supported Flash installation is not blocked.
Apple themselves no longer support OS X 10.8, as the last update for 10.8 was in 2015 ( Apple security updates - Apple Support ). It is not any company's responsibility to continue supporting old operating systems, and companies routinely stop supporting older operating systems.