Adding new segments to a destination account triggers a distribution. This involves LiveRamp matching the anonymized data to partner devices and delivering the output to the correct destination.
LiveRamp will also automatically trigger this process when new data is imported into your account, and every 5 days to keep the data active and up-to-date within a destination.
Once a segment has been configured for distribution, it will show up in the platform within 3 days of the initial trigger. More information can be found on this page.