It would best to have those Birthdays in a .csv file, which then can be imported into the dataSet in Xibo.
As for the user permissions, what permissions did you give that user?
Does he has view/edit permissions to the layout and all regions/widgets on it? (you do that by checking the Cascade the permissions checkbox on layout permissions form). You will also need to assign him permissions to at least, Layouts, Regions, playlists, datasets page and dataset itself.