Not to piss on the OP's parade, but, while liberal, the OSM license does require you to to give proper attribution to OSM in such a way than users are likely to notice it - I don't see that here.
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)
