Download the AutoCAD 2020 installer from your Autodesk Account (do not use third-party sites).
If you purchased a perpetual license of AutoCAD 2020 before the subscription-only model was enforced:
If you have a current subscription, Autodesk does not send you a physical card with a serial number. Everything is managed digitally. autocad 2020 product key and serial number
Enter the Product Key : 001L1 (for standard AutoCAD).
The 30-day trial of AutoCAD 2020 does require a serial number. You simply select "Launch as a Trial" during installation. After 30 days, you must enter a paid serial number to continue. Download the AutoCAD 2020 installer from your Autodesk
Q: What if I lost my Autodesk AutoCAD 2020 product key and serial number? A: You can retrieve your product key and serial number from the Autodesk website or contact Autodesk support for assistance.
If you purchased a digital subscription, the serial number was sent to the email address used during checkout. Enter the Product Key : 001L1 (for standard AutoCAD)
Run the installer. When prompted, select "I have my serial number" (do not select "trial" if you own a license).