The RadCloudUpload control does not upload files on its own. You need to specify custom implementation of an object serving as comunication layer between the control and a cloud provider. The actual uploading logic should be implemented in that layer. For this purpose you can use the Provider property of the control. It is of type ICloudUploadProvider and gets or sets the custom upload provider. It accepts any type of object implementing the ICloudUploadProvider interface.
For demonstration purposes we created sample implementations of providers that upload files to some cloud storages. You can find ready to run projects in our GitHub XAML SDK repository.