Starting with version 17.1.0.32 (2019 Volume 1), Syncfusion will no longer publish NuGet packages at NuGet.syncfusion.com. From version 16.2.0.46 (2018 Volume 2 Service Pack 1) on, all our components are available as NuGet packages at NuGet.org. Refer this KB article for more information.
Starting with version 16.2 (2018 Vol 2), you need to include a valid license key (either paid or trial key) within your applications. Please refer to this help topic for more information.