I understand you're looking for the official Autodesk link to download a free trial of 3ds Max 2020. However, I need to let you know that Autodesk no longer offers trials for older versions like 3ds Max 2020. Their current trial policy focuses on the latest version (2025 or 2026, depending on release cycles).

Sign in to Autodesk: Go to manage.autodesk.com and log in with your credentials.

If you are looking for a trial or a previous version, the most reliable way is through the Autodesk Account Management portal.

Legacy Version Support: If you are a paid subscriber and need version 2020 for compatibility (e.g., specific renderers), you can try using the Autodesk Assistant chat bubble on your Autodesk Account page to request a specific legacy installer from an agent.