I am not familiar with Linux, but I think the best way to find out is to ask Linux support. Select the downloaded XPI file to load it as a temporary extension in Firefox. Activate the 'Load Temporary Add-on button'. Select 'This Firefox' (or This Nightly) in the sidebar.

Load about:debugging in the browser's address bar. For more information on Flash Player and Google Chrome, see Flash Player with Google Chrome. So, it's not necessary for Chrome to download Flash Player separately. As Adobe will abandon flash, will the operating system be able to continue running these old versions of flash player? Download the latest version of ruffle for Firefox from the official download site. The Google Chrome browser (32 bit) includes Adobe Flash Player built-in.

But photobox request for upgrade remains. takes 30 seconds but 4 days later I still have had no success.

However, a question arose: these browsers do not have the built-in flash, that is, it is necessary to install it on the computer so that the visitor can interpret it. you need to upgrade Adobe Flash player on your browser.

Browser with flash player integrated