You need to take a bus from Durbuy (Barvaux) to reach the city center.
The bus company is TEC - line 99 Barvaux/Durbuy.
This shuttle bus runs every day during July/August. For the rest of the year, better to check the schedule here. There are other local buses that take you to the city center.
If you feel like walking it's a 3KM walk to the city center.