Turns out, Dropbox happily shares your data with others.
When you work with politically sensitive data, you might want to follow the example of the Konrad Adenauer Foundation and keep your data out of the public cloud...
https://dropboxbusinessblog.co.uk/protecting-everyones-right-to-education-how-collaboration-and-research-work-together/
https://nextcloud.com/blog/keeping-data-secure-at-a-globally-distributed-organization-konrad-adenauer-stiftung/