Once a user has landed at the Content Store for ArcGIS landing page, having been provisioned by their account admin, they authenticate using their existing ArcGIS credentials.
There will then be a workflow for a user to generate a SkyWatch specific account. Content Store for ArcGIS is a SkyWatch developed application, and requires a SkyWatch account to be created for use.
The activation link should appear in the email associated with your ArcGIS account.
Clicking 'Activate Your Account' will walk through a password generation protocol. Once that is complete, click 'Continue'. The account activation & linkage process will occur, and a user can then access Content Store for ArcGIS.