Refer: https://computingforgeeks.com/how-to-install-latest-adobe-flash-player-on-ubuntu-18-04-linux/
sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner"
sudo apt update
sudo apt -y upgrade
sudo apt install adobe-flashplugin
sudo apt-get install browser-plugin-freshplayer-pepperflash
Adobe Flash should now also be available on search menu too