Not sure if it's the version of WP causing this but here's my case. I did everything in the instructions and the plugin can't activate giving this error:
The Dev Staging Environment plugin is not installed correctly. Please ensure the web server has read and write access to the /wp-config.php file and click here to reinstall the plugin
I've given 666 permissions to both wp-config and the plugin folder with no luck. Also tried 777 though I knew it wouldn't make a difference.