This can be tricky. The infotainment system has a separate volume level for everything... The radio, your phone, built in apps, and Waze. The Waze volume can only be adjusted while Waze is speaking. So if the Waze volume happens to be set on zero, you won't hear anything. You need to try and adjust the volume upward when you think Waze is talking.
Another issue is you have to make sure your phone is connected to the car, blue tooth or USB, and it has to be selected as the device of choice. Plugging in the USB cable usually helps with this.
If course, make sure you have Waze set to give you auditory directions and that you didn't have the volume within Waze turned off.
Good luck. It will work. You just don't have your settings right.