From everything I have read and seen, they are just continuing the story. I think if they were going for alternate universe, they wouldn't have set it up I guess I see alternate universe as them changing what happened in the first movies to do what they want with the new movie. But that doesn't seem to be the case. They reference Hammonds failed attempts and how the Masroni bought the island and was able to complete what Ingen and Hammond could not. They had 12 years to fix the island, even Disney doesn't move that slow.