Don’t worry we’ll get it sorted. I think I know what the issue is and this is fixed for the next update. — Do you by chance have a lot of posts on your site? Like hundreds of posts?
If so, I think the issue is just that the Add Widget Area page is trying to list out all of your posts so they can be selected for assignments, but your server is dying in the process. I can provide a fix for you if you install the Child theme that came with your theme package you downloaded from ThemeForest. Can you do that? Or do you need me to explain that further?