sudo apt install curl

Now it’s time to add a new key to the list of trusted keys and resynch the package index files from sources

curl | sudo apt-key add -

echo "deb [arch=amd64] `lsb_release -sc` main" | sudo tee -a /etc/apt/sources.list.d/brave-`lsb_release -sc`.list

sudo apt update

Once you run the last command list above, you should see brave-apt xenial as shown in the screen capture below

Brave Browser Source Package Index File Update Ubuntu devPorto

And now for the installation of the Brave Browser