You can pickup anyone without knowing their address by sending them a pick-up request.
The only thing they need is a web-enabled device (computer/laptop/smartphone/tablet) that can receive an SMS or e-mail. Open the Menu and choose Meet Up:
Select Pick Up:
Click on Send pick up request and choose send it via SMS or Email:
When the person you wish to pick-up accepts the request:
(They can adjust their location on the map before sending it)
Their address is sent to your Waze app automatically:
After you choose Drive, they are sent to a web-page with a live map displaying your location en-route, and your ETA.