If you see it in the plugin page then it is properly installed. You now need to go to the admin/layout section and add it there. Enable the widget in all pages.
Finally, you'll need to logout. The plugin only shows the box to not logged in users.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
July 15, 2020: Q2A 1.8.5 released!