There's no such thing as a "V4 Addon Manager" folder, as it was somewhat separate from a "V5 Addon manager" folder or an "FSX Addon Manager" folder.
There's only ONE Addon Manager folder, and only ONE copy of the Addon Manager installed in any system. The only thing that changes from a simulator to the other one, are some difference in the enabled software modules so, for example, 32 bit Addon Manager is bglmanx.dll, V4 Addon Manager is bglmanx64.dll and V5 Addon Manager is bglmanx65.dll.
The installer will of course configure each sim correctly and pointing to only the files it needs to use.
So, even if you decided to override the default installation path, and install the ONE and ONLY Addon Manager in a folder named "D:/P3dv5 addons / Addon Manager", the only thing you'll achieved is just that confusing name but you effectively installed and configured ALL simulators to use that folder. Not that this would make any difference, since they will work anyway.
Unless, you made something entirely different, like selecting a folder for your V5 Addon, because you assumed you needed separate Addon Manager installations, and selected only V5 to install. This would surely cause a big mess, because you are not supposed to install multiple copies in different folders.
To prevent further confusion, I suggest doing as follows:
- Uninstall EVERYTHING from FSDT.
- Reply YES to the question "Do you want to remove the Addon Manager ?" - THIS is VERY important
- Check if still have other Addon Manager folders installed elsewhere. If you do, remove those folders manually.
- Reinstall everything, obviously using only the latest installers that supports P3D V5 as well.
- Choose a sane folder name which would make abundantly clear to you there's only ONE Addon Manager shared between all simulators, for example D:\ which will results in all FSDT products installing into D:\Addon Manager.