This site maintains a version history for VEGAS Pro where older files are stored for users with compatibility issues on newer hardware.
Downloading today is complex because the software is over 15 years old and the brand has changed ownership. Sony sold its creative software line to MAGIX in 2016. 1. Official and Legacy Downloads Sony Vegas 9.0 Pro Download
If you do not have a pre-existing license, finding a legitimate download for version 9.0 specifically is difficult. This site maintains a version history for VEGAS
