In permission settings, there is no distinction between account holder and non-user subscribers. While for reply and post (and most if not all moderate) functions which can be done via email there is nothing ambiguous, browse can only be carried out through the web UI, which handles permission through user authentication. Thus, for non-users, it is not obvious how to distinct the permissions for ones who subscribe and who do not.
In other words, for individual permissions, I would distinguish "subscribe" (for non-sr.ht users) from "browse" (for sr.ht users).
Perhaps just a hint somewhere within the interface that non-sr.ht "subscribers" will not be able to browse the archive through the sr.ht UI.