Treasures in the game (The Elder Scrolls Online)

You need the cards in your inventory to open the chests. (Maps can be found in all sorts of pots\chests. Either buy in the shop. Well, a pile of cards given to buyers a monthly subscription, like\traveler's set)

Thanks for the info,I just I have not come across maps

If the card is not present in inventory, then they will not display on the map