Many legacy resellers retain archives of old versions for existing maintenance contracts. You cannot simply download it from a public website, but you can request a by proving you own a valid license key for that version.
: Ensure your version of AutoCAD is compatible before installing. For instance, while version 17 works with AutoCAD 2019, earlier versions (like COVADIS 16) only supported up to AutoCAD 2018. Covadis and AutoCAD 2019 - Forums, Autodesk covadis 171 download exclusive
To ensure a secure and supported installation, users should access downloads through official channels: Many legacy resellers retain archives of old versions