Codeception seeInDatabase not found

I'm trying to write tests for my PHP backend with codeception. At one point I needed to test if there are changes made to the database.

I (tried) to follow the steps on the codeception tutorial but it wont work. I have installed the Db module via composer and added the config in my *.suite.yml and my codeception.yml, neither of them worked. Neither the AcceptanceTester class nor the FunctionalTester class contains any database related functions.

Every tutorial I found said "just use the functions", but without explaining how to get them/add them to the Tester. The tutorial on the codeception site just installs the module and without any explanation uses the functions, not even saying in which suite.

I also tried to create a Integration test, but couldn't find any source that describes how to do it properly. In my understanding (from the official page) I created a new integration.suite.yml file (see below) and created a test with it. But the tester still not recognizing any database functions.

codeception.yml:

extensions:
    enabled:
        - Codeception\Extension\RunFailed
        - Db:
                dsn: 'mysql:host=localhost;dbname=XXX'
                user: 'XXX'
                password: 'XXX'
                dump: 'tests/_data/dump.sql'
                populate: true
                cleanup: true
                populator: 'mysql -u $user -h $host $dbname < $dump'

integration.suite.yml

actor: UnitTester
modules:
  enabled:
    - Asserts
    - Db
    - \Helper\Unit