As Tom mentioned, try downloading whatever you need from the workspace of that notebook. You can access your workspace by clicking, Menu --> File --> Open.... when inside of the Jupyter notebook.
In case I use the File->Open I can edit single files, but it seems still not possible to download all sources/files in one shot ( for example for working on tour local env/notebook).
I can download single file, but I have to open and download one file at a time. They are a lot.