The Workspace page is accessible via the gear icon in the upper-right corner of the dashboard:
How to Use
Workspaces are the top-level container in Apps Creator. Workspaces contain a list of Brands for the workspace. This makes workspaces analogous to streaming platform "Properties" (which are sometimes commonly referred to as "Sites"). When provisioning of an Apps Creator workspace is performed from within the streaming platform dashboard, the workspace is associated directly with the site from within which provisioning was performed.
See the Brands documentation for additional information.