Once the data are released by ESO anyone can use them for scientific exploitation (see the ESO Data Access Policy).
Prior to that, non-public data obtained by the Participating Surveys can be used by the 4MOST Science Team (members of all 4MOST Participating Surveys) to publish papers, conference proceedings, presentations, etc., based on scientific projects that were previously registered with the 4MOST Science Policy Board. Any Science Team member may submit any scientific project using any 4MOST data for registration, although some restrictions apply to protect the core science goals of surveys. The details are regulated by the 4MOST Science Team Policies.
Non-public data of Non-Participating Surveys is only available to the originating surveys.