The Huelgas Ensemble is a renowned group around the musicologist Paul van Nevel. They specialise in medieval music from around 1300. So they are a bit out of their comfort zone here, I suppose. Rebelo was a seventeenth century composer from Portugal.
There is not much left of the music of Rebelo. Most of his music has been lost with the destruction of the royal music library in an earthquake in 1755. At the moment, only 44 pieces are known. Rebelo is also known for his adoption of the Venetian polychoral style, where polyphonic choirs were separated to acquire a more spacious effect.
There are not many recordings of his music, so this one is quite special.