How to install flash player for firefox on Ubuntu 20.10

I have tried to follow the steps recommended in https://linuxconfig.org/enable-adobe-flash-for-firefox-on-ubuntu-20-04-focal-fossa-linux But when I enter **sudo apt install flashplugin-installer** into my shell, it tells me **the package flushplugin-installer could not be found**. REMARK: I know flash is an old software virtually no one uses anymore, but I need it in order to view content embedded in newspaper articles that were published ten years ago.