First, head over to https://app.datatrics.com/integrations/ and search for CATSone.
Click on the "Install" button, and you will be redirected to the settings screen.
In the input box "Token" fill in your CATSone API key. To access the API, you will need a v3 API key. You can create an API key from the Administration settings page in CATSone.
After saving the integration, Datatrics will use the CATSone integration for syncing candidates and items to Datatrics.