Ottawa has excellent public transit called OC Transpo, and by the time of the conference it should be even better as two new light rail lines will be active.
Here are public transit directions to get to the Shaw Centre from the airport (most hotels are nearby). Until train lines 2 and 4 re-open it will suggest taking bus 97 and then train line 1, but train lines 2 and 4 will be open by the conference time. When the train lines are open, exit the airport onto the line 4 train platform on the airport arrivals level, at the far west end. You will need to transfer to line 2 destination “Bayview” (max 6-minute wait) at Greenboro, and then to line 1 destination “Blair” at Bayview; you would exit at Rideau station, which has indoor connections to the Shaw Centre and Westin Hotel.
Route planning app: Use the Transit app (available on the Apple App Store and Google Play) to find your way around. This app is developed in Montreal, but is used worldwide by many transit agencies. It uses real-time tracking by GPS on busses and trains, as well as crowd-sourced data from users to give you accurate timings.
Fares: To pay fares, you can use tap your Visa, MasterCard, Apple Pay (on your phone) and Google Pay (on your phone) on busses and light rail stations. When transferring, use the same payment method, and you won’t be charged for the second ride. More information is here.
Uber and Lyft also provide ride-sharing services in Ottawa, and ordinary taxis are available. But these will be much more expensive than public transport, and at peak periods may be slower.