Seems like a hosting problem 2 me. I`ve sometimes see such "Error" when trying to install themes on my test hosting (at GoDaddy.com).
Solution is pretty simple: Upload theme by FTP.
Or, there might be even othr reason for the problem.
When you installing the theme - r u sure that you use correct file?
You shoul upload nor the whole Corona.zip file which you get from ThemeForest.
Unpack it, and there, inside you`ll see the "corona'zip" fiel which weight 2,36Mb.
You need to upload THAT file.
If that is not the issue, when, just take that Corona.zip, unpack it, and upload all (whats inside of it) here:
You hosting folder/WP-CONTENT/THEMES/
So, at the end you`ll get: hosting folder/WP-CONTENT/THEMES/Corona (that folder is from your ZIP file).
After thth, go to your wordpress, in the Appearance menu - swithc the themes.