The Link Metrics section of the Bitly API contains various operations for generating link-level metrics.
To use the Choreos in this bundle, you'll need a Bitly OAuth access token which is used to authenticate your account. To retrieve an access token, register an application, and follow the instructions documented here.
Many of Bitly's API methods require an OAuth access_token for authentication. For testing purposes, or cases where you are only making API requests on behalf of your own account, you can generate a generic access_token (you'll need your Bitly developer credentials).