There's no thing called DL manager. Maybe you mean the "Addon Manager".
If you meant the Stand-Alone Addon Manager, "Stand-Alone" means exactly that: there's only the program with other support files that allows things like ParkMe or YouControl, but there's no scenery.
So, if the *scenery* you had installed wasn't 1.3 version, upgrading the Addon Manager won't help upgrading the scenery, since the Addon Manager doesn't include any scenery.
To upgrade the scenery to the latest version, you have to install the latest installer for the* scenery*, either the update patch or the full scenery, doesn't matter (the full it's just longer to download, that's it)
To check if you need the upgrade, check your full scenery installer: it will display its version either if you right-click on it and select "Properties"->"Details" OR if you launch it, in the first installation screen.