By default, collections are not moderated, which means any registered user of the Archive can add their works to the collection. The owners/moderators of the collection can still reject stories after they have been posted, if they are not appropriate.
If you set your collection to be moderated, all registered users will still be able to post, but their stories will not appear in the collection until they are approved by a moderator or owner. Approved members will be able to post automatically without manual approval.
Owners of a collection can edit the collection preferences and data, and also delete the collection entirely. Moderators of a collection can approve/invite members and add/reject stories.