To add an integration, go to your account and select "Integration". There, you'll get a full overview of all available integrations and can test the Delivery Status to ensure everything is running as expected.
Once you've added an integration, it may be connected at the account level, but please remember: it's not automatically applied to individual campaigns.
You must always configure the integration within each campaign for it to function properly. Please go to 'Add-ons' and enter 'Integrations':
Then you can choose one of the already available integrations here in the overview:
Then you can see your related integrations in 'My integrations', where you can set it all up: