If you want to active your Widget then you’ll need to use the following steps:
For every Widget you can use the widget which are shown to the left sidebar. For example: Text, Tag cloud etc.
You should keep the Text widget inside the Top 1-4, then enter the title and content then, save it and you can look your site, whether they are active or not.
Similarly you should use all the widget which are located in left side bar inside the right sidebar widget.
Or if you want to make your site same as demo, then you can purchase the demo installation package. After the demo installation you can replace the text from widget as well as you can remove it if you do not want it. And you can know that how to active the widget also.
And regarding the plugin they will work perfectly but widget are should be active or us in the site.
If there any further question/issue, then please let us know.