All the information you need to connect your integration to Adyen can be found in the Customer Area. The required information usually includes your merchant account name, your API key/API username and password, live endpoints, notification webhook urls, etc.
To specifically locate where this information can be found in the Customer Area, please refer to the Setup and integration section of our Development resources page.
Please keep in mind that the required information to connect your integration to Adyen is valid for the environment (test or live) you get it from. For example, your live API key can be retrieved from your live Customer Area only.