Hello,
That depends on the way the quarantine is configured. Administrators of the service configure the behaviour of the quarantine through the configuration portal (Services -> Anti-Spam -> Quarantine Settings). There, they configure settings such as quarantine notification frequency, if users can release emails directly from notifications, if users should have access directly to the quarantine, etc.
Through these options, users can receive a quarantine notification up to once a day with all emails that were quarantined. It is important to note however that as long as they are configured with access, they can log in their quarantine at any time, and they do not need to wait for a notification to review its content. With this kind of access configured, a user does not have to rely on an administrator to release an email on their behalf.
I hope this answers your questions.