Archives are full when they reach the size specified.
Because of the operating system security restrictions, the destination path cannot entered as a mapped drive. Instead, enter the destination as a UNC path (\\machinename\sharename\folder). This is also the case when browsing for the destination. Replace any mapped drive destinations with the appropriate UNC path.
For MSSQLServer and SQLServerAgent services to access remote machines to move the archives, the service accounts must be modified with the Service Control Manager. The destination (where the archive will be written) must be a shared device and the MSSQL services logon account must have Change permission to the destination folder.