The Archive log directory is configured with archive_command parameter and set to a local location on client to perform log backups. For more information, refer Configuring the PostgreSQL Archive Log Directory.
Commvault recommends to schedule several log only backups between full backups. To create automatic schedule, see Creating an Automatic Schedule for Database Log Backups.
To delete the transaction log files, see Enabling PostgreSQL Archive Log Deletion after Backup. If Archive Delete check box is not selected, the Commvault software does not prune the logs.