Issue Error Installing WordPress

[bluesky_c3]

I'm trying to install WordPress using the installer provided by the hosting and I can't, because I get the following error:

Error: The following error has occurred during the installation of application: Installation of WordPress at http://gallerybianco.com/ failed. Non-zero exit status returned by script. Output stream: 'PHP Fatal error: Call to undefined function mysqli_connect() in /usr/local/psa/var/apspackages/apscatalogvTeZ1T.zip641b2cfa-1c9d-0a/cache/scripts/db-util.php on line 53 '. Error stream: 'PHP Fatal error: Call to undefined function mysqli_connect() in /usr/local/psa/var/apspackages/apscatalogvTeZ1T.zip641b2cfa-1c9d-0a/cache/scripts/db-util.php on line 53 '.

Could you please tell me what should I do in order to fix this?