His first point of contact with Indian languages and philosophies was through Collier's Encyclopaedia. It introduced him to such ideas as rebirth, a concept found in various traditions (see e.g. here, here or here)
His first degree was in Indian Studies at the University of Utrecht, at an institute that developed into a centre of Tantric Studies and that has in the meantime been closed. His teachers included Jan Gonda, T. Goudriaan , Henk Bodewitz, Leen van Dalen , George Chemparathy, Kamil Zvelebil, Sanjukta Gupta, Karel van Kooij. He did his PhD and much subsequent work in Mysore, where he frequently visited the university and the Oriental Research Institute; and whereas his early interest in Jainism brought him to Karnataka, he also studied religious currents such as Vīraśaivism and Mādhva Vaiṣṇavism.
Through his close acquaintance with Bannanje Govindacharya, he began working on Madhvācārya and his writings, also those concerning the Bhagavadgītā. (The article he mentions may be found here.)
He would use the SSPRG, the Sanskrit Studies Podcast Research Grant, to learn Old Javanese.
For anyone interested in learning about Sanskrit for the first time, he recommends Pierre-Sylvain Filliozat's Le sanskrit/The Sanskrit Language.