my two cents on this film (spoilers)
1) I think the structure in the end what obviously a Dyson sphere
2) I think the story would have worked better if they were abducted by post-humans from a alternate universe instead of generic "aliens" (at least that would explain the numbers in the hull of the superstructure and in their tattoos) leading to number 3 and 4
3) the numbers 2.3.5.41 were coordinates on how to reach that specific universe/earth
4) the writer was more interested in the whole "goldfish" metaphor than in paying attention to details of the story.