Similar opening phrase, but from there on it is WAY more different from either "The Munster Cloak" or "Bannocks of bear meal" than either is from the other. It doesn't have a hint of the verse/chorus structure the British Isles tunes have.

I'd put the resemblance of the Spanish tune to the others down to fluke - a fairly natural riff that could have been reinvented anywhere that had the same sort of tonal vocabulary. (In Scottish music alone, you get the same sort of rising sequence in "Hey tuti tati", aka "Scots Wha Hae"). Once people got the idea of building a tune over a bass line (around 1600), you got very similar tunes reinvented all over Europe. Compare "La Folia de Espana" with the "Lament for the Bishop of Argyll" in the Macfarlan MS - no reason I know of to think there's a genetic relationship.

There was substantial sea trade between Scotland and Spain as far back as 1500 - Francisco Ayala commented on having encountered Scottish salted herrings at home. Fishermen were always an international community, and the Basques (next door to Aragon) got all over the north Atlantic. But we don't have any musical trace of this.

There is also a rather obvious historical connection between England and Aragon around 1500, but I doubt royal marriages ever did a lot to transmit folk tunes.