Copy the command, paste it in Terminal. Copied. Now paste it in Terminal.
brew install --cask cyrus-cai/lofi-lab/notchi
~ $
brew install --cask cyrus-cai/lofi-lab/notchi
==> Downloading notchi
==> Installing notchi
🍺 notchi was successfully installed!
~ $
Or hand it to an agent
Install Notchi on this Mac. Run brew install --cask cyrus-cai/lofi-lab/notchi, verify that /Applications/Notchi.app exists, then launch it. If Homebrew isn't available, tell me before installing anything else.