Because BNA is EOL, you cannot find it on a public, "click-to-download" page like a typical open-source tool. Brocade (now Broadcom) has moved all legacy software to their , which requires a valid support contract or a registered corporate email.
However, as of 2021, Broadcom (which acquired Brocade in 2017) officially Brocade Network Advisor. The software is no longer sold, and support has transitioned to newer platforms like Brocade Fabric Vision and Broadcom SANnav . download brocade network advisor