Adobe Acrobat 9 was released in 2008 and is no longer supported by Adobe. It's outdated software that may have security vulnerabilities. Adobe now offers (the free PDF viewer) and Adobe Acrobat Pro (paid version) with modern features and security updates.
That said, here's a short fictional story about someone in your situation:
She searched online: "adobe acrobat 9 download gratis." Dozens of sketchy sites appeared, promising free downloads. One looked convincing—a blue button, an old-style Adobe logo, and a "legacy software archive" label.