All prices quoted here are in Canadian Dollars.
Halifax is served by Halifax Stanfield International Airport (YHZ).
Most foreign nationals now need an electronic travel authorization before flying to Canada. This applies to all visa-exempt foreign nationals (for example, European citizens). It only costs $7 and can be done efficiently at the eTA website. The eTA requirement does not apply to U.S. citizens, nor to visitors who need an actual visa to travel to Canada.
The cost of a taxi or limousine from the airport to downtown Halifax cost is a flat rate of $63.
Shuttles between the airport and Halifax run on a fixed schedule every 2-3 hours. The cost is $22 one way, or $40 for a return ticket, per person. There are a fixed number of drop-off locations in Halifax (usually hotels). Beware that the last shuttle from the airport leaves at 10pm. Tickets can be purchased at the airport Ground Transportation desk. See the Airport Shuttle website for schedules and booking information.
There is a public bus between the airport and Halifax. It departs every 30 minutes during peak hours (6-9am and 3-6pm Monday-Friday), and every 60 minutes otherwise. The cost is $3.50 and exact change is required. The bus number is 320. You can find the schedule here. The bus stop is located outside the terminal, not directly in front of the terminal, but on the second road:
In Halifax, the bus arrives at Scotia Square Mall, about 2.3km from the conference location.