How to include nuovo/spreadsheet-reader in composer json?

Question

Composer

Hello!
Here is what is written in composer.json:

{
  "require": {
    "league/oauth2-client": "1.4.2",
    "nuovo/spreadsheet-reader": "0.5.11"
  }
}

But the error still comes out: Fatal error: Class 'SpreadsheetReader' not found
What to do? How to be?

Answer 1

composer update

Answer 2

Is vendor connected at all?
require_once(__DIR__.'/vendor/autoload.php');