This train is THE WAY to get from Pearson International in Toronto - to Union Station in Downtown Toronto. It smells brand new, is clean, lovely ticketing agents and saving money instead of using a car service app. Just follow the signs after customs/baggage claim to the left for "trains." You'll see the UP Booth near the end of the greeting hallway (past the Starbucks) and they'll direct you from there.
Hint: it may look like the train will leave without you, but if the green lights are lit on the train doorways, just press one and the doors will open right up! Look for the little green "elevator style" lights! Highly
impressed by this phenomenal and affordable service.