Custom drive for file storage

My project is to create a custom drive for file storage. I need to store documents so I'm looking for cloud storage. I am interested in user level access control. I expect the project to include the development of a secure system that guarantees data protection and privacy for users. The solution should also provide efficient access to data, with the possibility of easily scaling up or down as needed. Finally, the system should be fast, reliable, and cost-effective.