https://element.io/get-started

Installing the Matrix client Element is fairly straight forward on Ubuntu. You should be able to copy and paste the following commands in a terminal.

sudo wget -O /usr/share/keyrings/riot-im-archive-keyring.gpg https://packages.riot.im/debian/riot-im-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/riot-im-archive-keyring.gpg] https://packages.riot.im/debian/ default main" | sudo tee /etc/apt/sources.list.d/riot-im.list
sudo apt update
sudo apt install element-desktop