1. You need to Unlock the Captcha to publish to google plus.
To unlock the captcha, please go to the link https://www.google.com/
Now you will get the confirmation.
Now try to access the google plus account from the plugin.
2. If the first option is not working, please go to https://myaccount.google.com/lesssecureapps and allow to use less secure apps.
By default it is off and please make it to ON.