"You have to go to the domestic airport."
Whilst 'you guys' is certainly used in some dialects of spoken English it's very informal so it would almost certainly not be used in this context (i.e. a transfer desk employee instructing passengers how to reach their gate.) I think most would agree that amongst the many possible variations in any given translation the one closest to standard English is the preferable one, not a slangy colloquialism used by some speakers in certain areas.
While it may be colloquial and not very appropriate in a formal setting to say "you guys," the exercise should have some indication of the plurality of "you" in the English sentence if it is looking for the plural 你们 in the Chinese translation. Perhaps something like "you all" would be a better substitute.