Readwok - is an online text reader with a progressive viewing mode.
It is a tool to turn any plain unformatted text into a modern interactive format.
It is a way to read paragraph by paragraph, in order to read and process information more easily.
Double check the format of the uploaded file, and make sure it is one of the supported text formats (you can not upload an image only).
It is also possible that the problem is because of a bad connection or a large file size (more than 70MB).