Hub can be accessed using the Hub link in the navigation bar. It is where you'll find the stored documents and files that you have access to.
Hub is owned and controlled by your Blink administrator. They create the folders which live inside Hub and choose which Blink team has access to it.
You will only see folders that you have access to. In the example below, Christopher can see three folders called Events 2018, Finance and Profiles because these are all assigned to a team he is a member of.
In the admin panel, you can see that a fourth folder called Exec Files exists too, but only members of the Exec team can see it, so it is unavailable to Christopher.
Organisation administrators can create new folders and upload new files by opening the Blink admin panel and choosing Shared Content from the menu bar.