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.
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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.
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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.
GL )