This is a key, but often misunderstood, element of FAIR. The ‘A’ in FAIR does not necessarily mean ‘open’ or ‘free’. Rather, it implies that one should provide the exact conditions under which the data are accessible. Hence, even heavily protected and private data can be FAIR. Ideally, accessibility is specified in such a way that a machine can automatically understand the requirements, and then either automatically execute the requirements or alert the user to the requirements. It often makes sense to request users to create a user account for a repository. This allows to authenticate the owner (or contributor) of each dataset, and to potentially set user-specific rights. Hence, this criterion will also affect your choice of the repository where you will share your data.