Complex sentence: At some point during this period of freelance Buddhist practice, Kūkai had a dream, in which a man appeared and told Kūkai that the "Mahāvairocana-sūtra" is the scripture which contained the doctrine Kūkai was seeking.
Split into simpler sentences: At some point during this period of freelance Buddhist practice, Kukai had a dream. In the dream, a man appeared and told Kūkai that the "Mahāvairocana-sūtra" is the scripture which contained the doctrine Kūkai was seeking.