I see "(c) Mapbox (c) OpenStreetMap" in the bottom right of the map preview, so I assume it will also be part of the export/print. "OpenStreetMap contributors" and another clickable link in the footer would be better but I see reasonable effort in/on the end product.
edit: reading through other comments it's possible the author added the attribution only recently (after OPs comment)
edit: reading through other comments it's possible the author added the attribution only recently (after OPs comment)