Lund University is a Swedish authority and has the obligation to comply with Swedish law, including the personal data act (PUL). Dropbox is a service with servers in foreign countries, and the university lacks the control required by the law of any personal data that could be stored on this service.
See also the case of Enköping, https://www.datainspektionen.se/Documents/beslut/2011-09-30-enkopings-kommun.pdf (in Swedish).
The universities in Swede have, instead, through the cooperation body SUNET, jointly procured a service that accurately meets the legal requirements. This service is called Box. Also Office 365/OneDrive meets the requirements. If your work has the need of a web based service for storing and sharing documents and files, you should use Box or Office 365/OneDrive instead of Dropbox.
See also cloud services for a comparison.