Firstly apologies for the delay in responding and any inconvenience this may have caused. By default Blobs are organized in a flat listing rather than hierarchical. There is a good explanation in the documentation here, as well as some sample code. If you do not have hierarchical namespaces enabled you can simply use a delimiter character and folder in the blob name. There is a Stack Overflow question also asking about the GetDirectoryReference replacement and a GitHub issue that you might find useful. Please checkout the Quickstart with examples of creating containers and uploading blobs.
Since you would like to create a folder structure you might consider enabling Azure Data Lake Storage Gen2 hierarchical namespace. If you enable this you can find information on creating and managing directories here.
Hope this helps. Let me know if you have further questions or issues and I will be happy to help.
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