Complex sentence: The third boon was that Aravan should be married before the sacrifice so that he could get the right of cremation and funerary offerings (bachelors were buried), is found only in the folk cults.
Split into simpler sentences: The third boon was that Aravan should be married before the sacrifice so that he could get the right of cremation and funerary offerings (bachelors were buried). This third boon, however, is found only in the folk cults.