To connect :copper with CLINQ, please navitgate to Settings -> Integrations -> Contacts and select connect under :copper.

Here you'll need to enter your :copper usernamae (e-mail address used for your :copper login) and your :copper API key.

You can find your :copper API key in :copper under Settings -> Preferences -> API-Keys. If you haven't generated an API key yet, click on Generate to create one.