Install Element (formerly Riot) on Debian, Ubuntu or derivatives

All at once:

sudo wget -O /usr/share/keyrings/element-io-archive-keyring.gpg \
          https://packages.element.io/debian/element-io-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/element-io-archive-keyring.gpg] https://packages.element.io/debian/ default main" \
| sudo tee /etc/apt/sources.list.d/element-io.list

sudo apt update
sudo apt install element-desktop

Step-by-step …