When your subtitles are finished, you can click Complete button in the subtitle editor to mark them as complete:
However, in some cases this button or even the whole progression panel ("1. Type what you hear", etc.) can be missing.
1. I can see the progression panel, but not the button.
Usually this means that your subtitles have a problem that prevents them from being marked as complete - unsynced subtitles or subtitles without text.
Solution: sync or delete unsynced subtitles, delete or fill with text empty lines. In particular, check the subtitles at the end - this is where such problems often occur. When you've corrected all these mistakes, the Complete button will appear in the panel.
2. Neither Complete button nor the rest of the progression panel is visible.
Typically, this happens if your Web browser is significantly zoomed in or out compared to the default value.
Solution: start zooming in (CTRL [or CMD] + Plus) or out (CTRL [or CMD] + Minus) your browser to restore the progression panel. In many browsers, CTRL+0 keys restore the actual size (100%) in a single click.