Help with uploading an SVG file

After I press "SVG options" and "Upload SVG", a window appears with an "x" to exit, the following text: "This advanced feature requires knowledge of how SVG files work. If you want to learn more, click here.", with a link on "click here", and a "Choose a file" button below it". However, pressing "click here" or "Choose a file" does nothing. Only the "x" works. How else am I meant to upload the file?

Any ideas are very welcome.