How do I enable PHP extensions on CentOS to finally finish installing/configuring Drupal?
On CentOS, you should have an icon in cPanel for "PHP Selector":



In CloudLinux:



Make sure all of the PHP extensions installed by Yum are enabled &amp; save the settings. Then create or open the info.php page for your domain to confirm the configuration. The problem should be fixed on the Drupal 8 status report.

Note: If you are having problems with installing PHP extensions for a web server running Drupal, consider installing Composer on CentOS. Composer is designed to streamline dependency management in PHP and manages the particular download files required by Drupal 8 modules specifically.