To use the SAP web repository, we created an RFC user and we released the function  WWW_GET_MIME_OBJECT with transaction SMW0. Are any other actions needed?

Please check that the RFC user has the necessary rights (see documentation). We also recommend you use the GuiXT script caching ("Replication  Yes" in guixt.ini) and the "Versionnumber" statement (see documentation) to minimize network traffic.