Problema durante l'installazione

Buongiorno,
stavo provando ad installare sul mio server invoice plane e dopo che ho inserito le credenziali del database ottengo questo errore:

An uncaught Exception was encountered

Type: Error

Message: Call to undefined function mysqli_init()

Filename: /volume1/web/fatture/vendor/codeigniter/framework/system/database/drivers/mysqli/mysqli_driver.php

Line Number: 135

Backtrace:

File: /volume1/web/fatture/application/third_party/MX/Loader.php
Line: 177
Function: DB

File: /volume1/web/fatture/application/modules/setup/controllers/Setup.php
Line: 280
Function: database

File: /volume1/web/fatture/application/modules/setup/controllers/Setup.php
Line: 217
Function: check_database

File: /volume1/web/fatture/index.php
Line: 325
Function: require_once

Qualcuno mi riesce ad aiutare? Uso php 7.0
Grazie
Stefano

My Italian is a bit rusty, but I see an error with mysql_init not found. Can you see if mysql is installed on the server?