I wouldn't download that old .Net 3.5 package for VS 2019. Chart class is part of .Net Framework 4+.
Are you sure you created a Windows Forms App (.Net Framework) project, and not a Windows Forms App (.Net Core) project?
For Windows Forms App (.Net Framework) project Chart the control is present in my VS 2019 install. If yours isn't maybe you removed it sometime? It can be readded by right-clicking Data section in toolbox and select "Choose items...", select the Chart control from System.Windows.Forms.DataVisualization assembly.
For Windows Forms App (.Net Core) project the Chart control is available as a prerelease Nuget package, search System.Windows.FormsDataVisualization and include 'prerelease' packages.