I'm amazed they were only off by 63 miles, given the article claims dead reckoning was so inaccurate. I'm even more amazed they knew where they were relative to their destination after 66 days of dead reckoning.
Crucially, that's 63 miles North of Virginia. Latitude is relatively straightforward to measure. It's pretty well given that if you sail west from Northern Europe, you'll hit North America. Hitting it at your intended latitude might depend on the winds, but one you bump into it, it should be pretty easy for a competent navigator to tell you how far off your target you were in latitude. Given decent maps, figuring out longitude is probably not a tall order either if you know your latitude and you're on the coast.