The document provides instructions for installing Nessus vulnerability scanner on Ubuntu 16.04, including downloading Nessus, installing required packages, configuring the Nessus daemon, setting up the web interface, registering the scanner, and obtaining plugin updates. Key steps include accessing the Nessus download page, following install instructions in the user guide, enabling the Nessus service, allowing traffic on port 8834, and registering the scanner with a valid activation code.