Atlantis is sadly just a legend which is theorized to be created by Plato. Within the article you provided, it states: "Plato had not contained so much truth about the human condition, his name would have been forgotten centuries ago.
But one of his most famous stories—the cataclysmic destruction of the ancient civilization of Atlantis—is almost certainly false. " There has been no evidence out there to prove that Atlantis exists outside of fables.
Another article from Discover states that: "Atlantis: the legendary island that sank beneath the waves in the distant past, taking down with it an advanced civilization. Is it possible that we will ever find it? Or, more importantly: Did it even exist?
The short answer to both: No. All available evidence indicates that the philosopher Plato, sometime around 360 B.C., invented the island nation in order to illustrate a point about the dangers of aggressive imperialism" (https://www.discovermagazine.com/planet-earth/where-is-the-lost-city-of-atlantis-and-does-it-even-exist). So to answer your question completely, Atlantis is a legend created by Plato, with no evidence causing the story to seem real.
There is however a "lost continent found under Europe" that some people call Atlantis, but this continent is actually called "Greater Ardia" Which was according to CNN "It’s the size of Greenland, and it broke off from North Africa, only to be buried under Southern Europe about 140 million years ago" (https://www.cnn.com/2019/09/23/world/lost-continent-europe-scn-trnd/index.html#:~:text=The%20continent%20is%20called%20Greater,about%20140%20million%20years%20ago.) Plato was also around 360 BC and not 140 million years ago so that diminishes the theory of this potentially being the Atlantis he talks about.