I have a Magento 184.108.40.206 installation on Windows 2012 R2 and IIS 8.5. When I attempt to login to Magento Connect the login screen shows an error text "Unable to write to the configuration file." Also, when I attempt to login the page just loops back to the Magento Connect login page. I've opened the permissions on the config file, not sure what the issue would be. I'm new to Magento, so please be gentle
Personally, I don't recommend installing packages through the Magento Connect manager. You should always review the code before installing what you need to install on the platform.
One way to do this is by copying and pasting the extension key from Magento Connect on this website: http://freegento.com/ddl-magento-extension.php
By doing that, you will be able to direct download the extension/language pack code and review it. Then you just have to install the extension like any other extension.