Installing Sample Data for Magento 2 Error

[magento0027]

Hi there. I am trying to install Magento with Sample data on my laptop. I followed this instructions :http://devdocs.magento.com/guides/v2.0/install-gde/install/sample-data-after-magento.html. After doing "composer update" I tried to run: "php bin/magento sampledata:deploy" but it is showing me error:

[root@localhost magento]# php bin/magento sampledata:deploy
Failed loading /usr/lib64/php/modules/xdebug.so:  /usr/lib64/php/modules/xdebug.so: undefined symbol: zend_unmangle_property_name
./composer.json has been updated
Loading composer repositories with package information


                                                                             
  [Composer\Downloader\TransportException]                                   
  The 'https://repo.magento.com/packages.json' URL required authentication.  
  You must be using the interactive console to authenticate                  
                                                                             


require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-update] [--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [--sort-packages] [packages1] ... [packagesN]


There is an error during sample data deployment.

What can I do to fix this? Thank you.

[maddyC]

You havent set your authentication for repo.magento.com. please follow instructions here http://devdocs.magento.com/guides/v2.0/install-gde/prereq/connect-auth.html

[magento0027]

I did that already but it still won't work.

[Dmitry_Fedyuk]

The authentication error is normal when installing the sample data after Magento 2 is already installed. 

It is described in documentation: http://devdocs.magento.com/guides/v2.0/install-gde/install/sample-data-after-magento.html#authentica...

[magento0027]

Hey, thanks for the reply. I know it is "normal" . After I've seen that error I tried what was written on the instructions:

If the error displays, change to your Magento installation directory and run composer update, which will prompt you for your authentication keys.

But, I still encounter that's why I posted my problem here . Thank you, I hope you can help me resolve this.