Pearson Airport is the main Toronto airport, though a little West of the city. Its booking code is YYZ.
A new and popular/well-liked way to get from Pearson to right beside the conference hotel (5 min walk) is this train: https://www.torontopearson.com/en/toandfrom/upexpress/##.These are other methods: https://www.torontopearson.com/en/toandfrom/ground/##
Another nearby airport is Billy Bishop (YTZ). It is on an island just South of the city. There is a shuttle that drops off pretty close to the conference hotel (10 min walk) as well: https://www.portstoronto.com/shuttles/index.html To get to the shuttle from the island there is a ferry from the airport to mainland and there is an underground tunnel.