San Albertus Island, Malta

Sorry if this is a dumb question. But how do I get access to San Albertus Island? I currently have 6 sites and I can’t seem to find that island? What do I need to do to access it? I currently have 15/30 stars from my 6 parks. Do I need more? I am trying to get the marketplace but the game doesn’t make it clear on what to do since I can’t find that island.