(as I bought all FSDT products, why should I install them with other installer?, I download them from FSDT website , and Install them from the files I have download from FSDT)
Fact you bought them, doesn't automatically mean you installed correctly using their own installer. That error seems to indicate you haven't installed them.
I aware that all FSDT softwares install to what you mention above. and of course I do not install FSDT software manually.
You said yourself you did that:
this issue I have since P3d V3, as I add scenery manually in P3D V3, also in FSX.
Which is confirmed by the error you got.
I run the installer TWICE as I know that I have FSX and P3D.
If you had, you wouldn't have that error. The error seems to indicate you installed in one sim, and added the scenery manually in the other sim, which is what you said you did.
Unless you meant something else with "I add scenery manually in P3D V3". In that case, please clarify what you really mean with this.
the problem is that couatl restart it self the couatly scripting, and the cause of that I could not see any building of each FSDT airport I installed (from FSDT installer )
The problem of Couatl restarting itself is not relevant. It's NORMAL that Couatl would try to restart itself when there's an error. The issue is, the error won't appear if you install the scenery using the scenery installer in BOTH sims.
and as I mention earlier that , I have to install the stand alone AddOn manager, but sitll the same issue
Since your error is caused by not having an object that comes with the SCENERY installer, because the installer hasn't been run, installing the Stand-Alone Addon Manager won't change anything, since the Stand-Alone Addon Manager installer doesn't come with any objects that belongs to a scenery. They only came with the full scenery installer, and that's what you must install.
Maybe you used the P3D Migration Tool ? That might explain why, even if you ran the scenery installer, the scenery was installed in the wrong sim, because what the Migration Tool does, is to fool installers that recognize FSX only, to go in P3D instead. Which means, it MUST be turned OFF when installing products that DO recognize P3D, which is the case with all our products.
Or, maybe you ran the installer, but haven't paid attention to any errors that happened during the installation ? That might also explain why the files are missing: the installation was aborted for some reason, so no all files have been installed, but of course this cannot happen without you realizing it, because you should have seen errors while installing.