got same problem. No error messages. So, if the program shows active, but not in the FSX scenery files it's not running?
If a scenery is not in the Scenery Library, it won't work, that's for sure.
The issue is, I see from your 2nd screenshot that you have an area titled "Las Vegas" in the topmost area of the Scenery Library. Is that supposed to contain FSDT KLAS ? Since our installer doesn't create an area named "Las Vegas", but "Fsdreamteam Las Vegas" instead. Assuming this IS FSDT KLAS, that seems to indicate you tried to create the area on your own, but that shouldn't be necessary, because the installer WILL DO IT.
If you haven't seen any error message while installing, it means the installer DID IT, but if your FSX doesn't show it and you had to manually add the Scenery Area, it means FSX is for some reason reading from the wrong scenery.cfg, and that's likely caused by the Compatibility mode enabled. If FSX is not reading the correct scenery.cfg, for the same reason the Addon Manager is not reading it too, that's why it tells the scenery is "not installed in the Scenery Library", so it's not displaying the scenery.
Note that, it's also possible the effects of the Compatibility mode might happen even if you have a 3rd party add-on that starts with FSX (or that starts FSX by itself) running in Compatibility mode so, everything that starts with FSX must have every setting on the Compatibility page DISABLED.