The contact information doesn't match what is already associated with the serial number when the product was registered. This can happen if there is a change to your name, the company name, or your address after the product was registered. Keep your contact information up-to-date using Register Once. There, you can add an account with your current information, register products to that account, and delete your old accounts, or those with outdated information.
Otherwise, visit AVA (Autodesk Virtual Agent) to resolve the issue and automatically receive an activation code or connect with an agent. Provide your serial number, request code, and contact information
Note: For single-user subscriptions, you can usually sign in so that a serial number is not required. You may see a Stand-alone license type for 2017-2019 products, but a User License type for 2020 and later product versions.
When you purchase new seats of Autodesk software, Autodesk may send you a serial number and product key, which you use to generate a license file. You can also find this information in Autodesk Account. 2b1af7f3a8