Generally the answer is: they "spent" the money on "intellectual property" licensed to them by a subsidiary in Ireland (patents, brand name, software license) where that subsidiary pays zero takes through some accounting trickery[0] and moves that money offshore to Bermuda or Caymans. So the main company makes zero profit in markets outside Ireland because coincidentally licensing expenses exactly equal the gross profits of the company - and thus pays zero taxes anywhere ever.

[0] formerly the "double Irish" international tax loophole, nowadays there's a different "Irish patent box"