my old one must have been corrupted or something.
No, it wasn't corrupted, is that you had to download the one that is online now, we had to make some changes that weren't updatable just by downloading the .dlls online as the regular installers do, but required to re-download the Addon Manager.
Of course, all the sceneries installers have been updated as well so, if you download any scenery right now, there will be no need to update anything.