Adobe Flash Player Ubuntu 18.10 [duplicate]
Solution 1:
Enable Canonical Partners Repository:
sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner"
Install Adobe Flash Plugin:
sudo apt update
sudo apt install adobe-flashplugin browser-plugin-freshplayer-pepperflash
Reset your browser and you should be all set.
Source: https://websiteforstudents.com/install-adobe-flash-player-on-ubuntu-18-04-lts-beta-desktop/