The system clock might be wrong. Also, ensure you are not using a VPN. If you have used a 3ds Max trial before on this PC, Autodesk tracks via hardware ID. You will need a clean Windows install or a virtual machine for a new trial.
To download a free trial of Autodesk 3ds Max , you should use the official Autodesk Free Trials page Important Note on Version 2020: Autodesk typically only offers the three most recent versions download 3ds max 2020 free trial version autodesk link
Avoid third-party “crack” or “keygen” sites. Only download from Autodesk.com or within your Autodesk Account to avoid malware. The system clock might be wrong