For the best Scoop experience, it’s usually best to be patient and wait for a few minutes for your fellow carpooler to be ready. When in doubt, you always have the option to contact them directly by tapping 'Trip Details'. Scoop also encourages carpool matches to reach out to one another prior to the start of the trip.
If the other carpooler is running late and you're unable to continue waiting, be sure to cancel via the app by selecting "I can't find my carpool buddy" or "My carpool buddy can't make it". This will immediately notify the other carpooler, and the cancellation will then be applied to them because they were unable to make the carpool.