Installing Drupal

I am trying to install Drupal 8.0.5 on Apache 2.4.6 on CentOS 7, with PHP 5.6.19. But in the web GUI for finalizing the Drupal installation, I get a problem on the requirements page. It says "PHP extensions disabled. Drupal requires you to enable the PHP extensions in the following list... gd"

I have installed, with yum install these packages: gd, gd-devel, php-gd, php-pdo php-mbstring, php-xml.

I'm trying to install Drupal 8 on my server (PHP 5.6).
Copied the file, extracted and when I access the site URL it displays the following error:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

I have done numerous installation of Drupal 6 & 7 before and this is the 1st time I have this issue. Even tried different D8 versions.
Followed the requirements on this link: https://www.drupal.org/requirements

I have installed Virtual Machine with Drupal on Azure.

When I open it's static IP address, it shows me Welcome to user's Site page.

When I access to my VM via FTP there are multiple folders in /opt/bitnami/apps:

1. bitnami
2. drupal
3. phpmyadmin

My boss gave me backup for drupal site which are compressed in tar.gz file:

1. website source
2. sql file

Website source file has code folder which contains a lot of other folders, images and php files.

Is there a SaltStack .sls file, Puppet manifest, or Ansible play-book to install Drupal? I'm interested in full installations without using the web-based configuration tool. Is it possible to not use the GUI and install Drupal?

I am using CentOS 7. I have installed MariaDB 5.5 and Apache 2.4.6. I tried to install Drupal 8.0.5. It seems like it was installed correctly. I followed some directions on DigitalOcean's website. The problem is that the web-based Drupal page is not there. I open a web browser and type in the IP address of the CentOS server. I see "Testing 123." This is the generic Apache page. The Apache service is up and running. I reinstalled Drupal. I get the same problem. What did I do wrong?

Hello!

When I want run my drupal server my console throws it:

adam@adam-desktop:~/projects/terminal/drupal-8.0.5$ drupal server

/usr/bin/php5 -S 127.0.0.1:8088
phar:///usr/local/bin/drupal/bin/..//config/dist/router.php

[OK] Executing php from /usr/bin/php5.