This is answered in the bold part of the following sentence taken from the Orthanc Book:
"Non-technical audience (physicists, patients, administrative staff...) might expect an user interface that is more user-friendly than Orthanc Explorer, and/or that integrates more features (such as language translations, sorting resources, access control lists, tagging images, beautiful layout, tunable anonymization, modification of instances, paging if many patients, handling of timeouts, login/logout...). If you need such a more advanced user experience so that Orthanc better fits your clinical workflow, you will have to develop a separate, custom Web interface on the top of the REST API of Orthanc, maybe as a plugin."