The Spanish (and the rest of Europe) were pretty nearly always engaged in the eternal war against the dreaded Turks in the Balkans.
Croatians were regularly used in the Turkish military ~ whether as cannon fodder or just haulers of wood and drawers of water, they were there.
Consequently they were regularly taken prisoner by Christian forces ~ and since Croatians were Christians they were not immediately killed.
Croatians also ended up in the Turkish fleets in the Mediterranean. Most of their opposition there came from Spain. They took POWs, including Croatians, to South Carolina (Carolana in those days). The smart ones promptly escaped and fled North to Albermarle Sound, et al.
And all of that seems to be a pretty far fetched background to "Croatan". That is, until you find out that Captain John Smith, the first Governor of the Jamestown colony, had been a Turkish POW. He spoke Turkish, and the belief was that every tribal group up and down the coast of North America had one or two Turkish speaking former Spanish POWs available for communication.
Smith was picked to be Governor because of that belief ~ and given the ease with which he was able to get about I believe it to be true.
There were also, at the time of the English landing in what is now Virginia, well over 20,000 persons of European descent already living in what is now Maryland.
How they got there and who they were is a doggone good question. The "record" is clear that they were totally illiterate. No doubt the archives in the Prado have some information about these folks ~ every now and then something new pops up there ~ e.g. Columbus' "first" First Voyage in 1486!
“The “record” is clear that they were totally illiterate”
First victims of public education? (humor)