Why? Will customs not let them in?
No the dogs have to ride in the cabin of the plane - they offered to buy seats for the dogs. The problem is with a commercial airline and they are looking for the funds to hire private airline to take the dogs in with them.
This problem may have been solved already and the dogs may be on their way to Aruba, some of the team is already there.
Equus searcher guy didn't say why the regular search dogs hadn't been brought to Aruba, but surely either the FBI or Aruban LE used search dogs in the past weeks looking for N. Most likely, Equus search believes N is dead and there's no point in bringing their regular search dogs, a reasonable assumption after all this time.