A login widget is out of scope for this plugin. You should search for such a widget elsewhere. Perhaps what you need is a membership plugin?
This is also true for the theme. I do not offer any themes. The UIs are tested with the standard WordPress themes. If you want you can customize appearance of the UIs with the Customizer, or with custom CSS. If you have any questions on how to do specific things with CSS and the UIs, maybe I can help.
P.S. I have moved your post to a new thread since it was unrelated to the other thread.