in localhost xlsx export is working good but in hosting(using Hostinger) shows class not fount class already exist in ci3

Question

An uncaught Exception was encountered Type: Error

Message: Class "PhpOffice\PhpSpreadsheet\Spreadsheet" not found

Filename: /home/u764710592/domains/pemserp.com/public_html/sandbox/application/controllers/Reports.php

Line Number: 77

Backtrace:

File: /home/u764710592/domains/pemserp.com/public_html/sandbox/index.php Line: 315 Function: require_once

  $spreadsheet = new Spreadsheet(); // Error Line