This duplicates topic:
but here is my problem: I clicked “share” for the notebook and set an email address, but the person with that email address gets a “not found” message. I changed to the Classic interface and clicked “link share” and the person with the invitee address (and anybody, which I don’t want) can access the notebook. What is needed other than clicking “share” and entering an email address to enable sharing? Also, where is this basic share and link share option documented? Can the Observable Introduction notebook be expanded with documentation on this?