I followed the steps shown below, but Signal is not showing in my applications folder.
Steps to install on Linux
Open your terminal.
Confirm you have APT.
Enter the following three lines into your terminal.
wget --quiet --output-document - https://updates.signal.org/desktop/apt/keys.asc | sudo apt-key add -
echo "deb [arch=amd64] https://updates.signal.org/desktop/apt xenial main" | sudo tee -a /etc/apt/sources.list.d/signal-xenial.list
sudo apt install apt-transport-https && sudo apt update && sudo apt install signal-desktop
The instructions came from here: