Throughout all the series of DC Comics on The CW there have been references to several characters of Justice League, being Atlantis is one of them, so that could also be the form in which it appears Aquaman in the Arrowverse.
In the last two seasons there have been references to the hero that is interpreted in the Universe Paving of DC Comics (DCEU)by Jason Momoabut until the moment has not appeared.
Although The CW has not always been authorized to present to the larger members of the team DC, the rules seem to be evolving season after season, with the appearance of Superman and Lois.
The greater alignment of the Justice League is becoming a part of Earth-Prime on The CW. However, some characters still have not been declared to be specifically or even not directly mentioned by name.
It has been established that Batman has been missing in the Arrowverse for a few years, which allowed Kate Kane to become the new protector of Gotham City.
‘Batwoman’ has also confirmed that a version of Wonder Woman is out therewhile ‘Legends of Tomorrow’ revealed that Themyscira existed in Earth-1.
Aquaman has been the subject of ridicule by the existence of Atlantis that began on the second season of ‘The Flash’, despite not being referenced by the name, because in the pilot of the series starring Grant Gustin had been a reference to Arthur through a scene removed when Joe West says that Barry investigates the story of a man who could talk to the fish.
The form in which it appears Aquaman in the Arrowverse, you get to do it, is still unknown, but most likely with a visit to Atlantis and the viewers to get to know Aquaman, either at a junction or through a story in one of the programs.
Visually, it can be difficult to show Atlantis viewers, which would require a very heavy and expensive effects, but see it could be to the liking of the fans.