What do you mean by synchronisation?

Through the synchronization process you get updated data about your Twitter account (new followers, unfollows, people you’re not following back, etc.). This process is automatic, and you don’t need to synchronize your account, as Audiense does it periodically and notifies you when it’s ready.

However, you can manually sync your account using the "request synchronization" button above the community stats panel on your dashboard (to access, click on your account logo in the dashboard under "My Twitter accounts".