Street Parking Spots that will become available will appear as blue pins (by default anybody leaving in the following 10 minutes will be displayed, but you can change this and see all by tapping the filter button). Orange pins are street parking spots where a driver just left (orange pins expire in 2 minutes).
Once you have found the street parking spot you want, hit the Opt In button and the other driver will be notified that you are interested in the street parking spot they are leaving
https://play.google.com/store/....apps/details?id=com.
https://apps.apple.com/app/id1502956115?mt=8