AEM Assets is an application on the AEM Platform that allows our customers to manage their digital assets (images, videos, documents and audio clips) in a web-based repository. AEM Assets includes Metadata-support, Renditions, the Digital Asset Management Finder and the AEM Assets Administration UI. Review here for more FAQs - https://helpx.adobe.com/experience-manager/6-4/assets/using/medialibrary.html Thanks.
AEM and CC are different offerings and until I am not sure about use -case its hard to share full info. If AEM Assets repo access is required then yes you need one AEM Assets for your team/group/company