A centralized network share makes sure that copies of transaction logs are available to all replicas within the Availability Group or for non-Availability Group configurations, a centralized backup of transaction logs. If the transaction log backups were created on more than one availability group replica, those transaction logs are still accessible and can be used for tasks such as up to the minute restores, database reseeding, and using a clone as a replica.
You can use the Configuration Wizard to set a network location as a centralized location for copies of transaction logs. At the time logs are backed up, the backups are copied to this share. You can do this either as a step in the initial configuration, or as a separate task.