Can't create Jupyter notebook on brand new Machine Learning and AI droplet

I set up a new Machine Learning droplet just a few minutes ago, logged in and got my Jupyter URL following the instructions here, but I get the following error trying to make a new notebook using any kernel:

An error occurred while creating a new notebook.
Forbidden

Here’s what looks like a relevant entry from syslog (i.e., it appeared as I clicked “New Notebook” as I was tailf-ing):

Mar 28 12:09:14 machine-learning-and-c-2-4gib-nyc3-01 bash[1386]: [W 12:09:14.081 NotebookApp] 403 POST /api/contents ([ORIGIN IP ADDRESS]) 2.91ms referer=http://45.55.37.63:8888/tree

I’m going to destroy this droplet so I don’t have to keep paying for it while I wait for an answer, but I’d be very interested in a solution.