All Ubuntu LTS 20.04 on Intel/AMD (codename Focal Fossa) distributions should be supported, prefered variant is Xubuntu:

The recomended way is to enter one command after another, do not copy them all at once. :)

sudo wget -O - http://dicaffeine.com/repository/dicaffeine.key | sudo apt-key add -

echo "deb [arch=amd64] https://dicaffeine.com/repository/ bionic main non-free" | sudo tee -a /etc/apt/sources.list.d/dicaffeine.list

sudo apt update

sudo apt install -y dicaffeine

Please use the standard system update tools, you can always update manualy using the console commands:

sudo apt update

sudo apt upgrade -y

sudo reboot