If Proxy requires authentication: enter Proxy and Credentials in Autodesk Desktop App.Check Internet Option (in Internet Explorer) for "Automatically detect settings" is turned off or turn on Automatically detect settings and Use a proxy server." Then enter the Proxy IP-Address + Port.Make sure Autodesk software is not restricted from accessing the domains listed in the article: Which URLs/Protocols need to be white listed for Autodesk Subscription Licenses.
Note: If AutoCAD version is 2018 is being used, install the Autodesk License Service (圆4) - 5.1.5 Hotfix installation. To change the status of the service to 'Running', right-click its empty Status cell and select Start from the context menu.In the Properties dialog, use the drop-down menu to change Startup Type to 'Automatic' and click OK.Consult with an IT administrator if necessary. Note: If the service cannot be started, make sure the Windows profile being used has enough permissions. In the Startup Type column, right-click 'Manual' and select 'Properties'.
Option 1: Check whether the FlexNet Licensing Service is running for versions 2017 to 2019 Using the incorrect account information will always result in the error. Note: before attempting any of of the solutions below, confirm that the correct account information are being used to sign into the product. Otherwise, refer to the following solutions: If this error occurs on the system that has LogMeIn installed, refer to "The License manager is not functioning or is improperly installed" on systems with LogMeIn installed.