Sharepoint - C# CSOM Create Folders in Lists programmatically

Try adding the following code for folder creation.

 //Enable Folder creation for the list
 list.EnableFolderCreation = true;
 list.Update();
 context.ExecuteQuery();

 //To create the folder
 ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();

 itemCreateInfo.UnderlyingObjectType = FileSystemObjectType.Folder;
 itemCreateInfo.LeafName = folderName;

 ListItem newItem = list.AddItem(itemCreateInfo);
 newItem["Title"] = folderName;
 newItem.Update();
 clientContext.ExecuteQuery();