public PortalItemType PortalItemType {get;}

//user content previously from...
//var userContent = await portal.GetUserContentAsync(owner);

var packages = new List<PortalItemType>
{
  PortalItemType.BasemapPackage,
  PortalItemType.GeoprocessingPackage,
  PortalItemType.LayerPackage,
  PortalItemType.LocatorPackage,
  PortalItemType.MapPackage,
  PortalItemType.ProjectPackage,
  PortalItemType.ScenePackage,
  PortalItemType.RulePackage,
  PortalItemType.VectorTilePackage
};
var folder = @"E:\Temp\PortalAPITest\";
foreach (var di in userContent.PortalItems.Where(pi => packages.Contains(pi.PortalItemType)))
{
  var path = System.IO.Path.Combine(folder, di.Name);
  await di.GetItemDataAsync(path);
}