Justin Greer on "Can't add plugins or themes: WordPress could not establish a secure connection"

I have seen putting

define('WP_HTTP_BLOCK_EXTERNAL', false);

in your wp-config file work.

Also check to make sure that your server's 443 port is able to be used. I know it sounds weird even if you don't use SSL.

Another resolution was to make sure that the connection to WP.org is not being throttle to horribly,. To slow of a connection will throw the error too.

One more thing. You will and I promise have issues with your second install running on Windows. You have whitespace in the relative paths which is a big no no for web.