Open an Instagram connection

The authorisation_url of a pending Instagram channel, as POST /robots/{robot_id}/channels returns it.

You never call this from your server and never build the URL: send the page owner’s browser to authorisation_url exactly as returned. It needs no API key and continues to Instagram’s login. Opening it again (a refresh, a second tab) works until the handshake completes or expires; after that it answers 410, and you connect the channel again for a new link.