During install I noticed a message stating "Python not installed".
No, you probably see a similar message (there's no such message in the installer), stating that a some product wasn't installed so, no Python support file for it is installing, which is absolutely normal and not an error. If you don't have, let's say, XPOI installed, it wouldn't make much sense installing its support file.
I tried to run it as Administrator and got the message "The file or directory is corrupt and unreadable".
First, you can't run Couatl.exe directly, it won't do anything. But it shouldn't display such error. In any case, the correct way of checking if the file has been installed correctly in your system, is not trying to run it manually (because it won't work), but to check for its Digital Signature.
Right-click on it, select "Properties", select the "Digital Signature" tab, check if the Digital Signature is still there and, click the Details button to verify is still VALID.
If it's not valid, than it's sure the file has been corrupted by something in your system. The most likely cause is the antivirus that corrupted it by mistakenly trying to "heal" a non-existent threat.
- Uninstall GSX. Reply YES when asked if you want to remove the Addon Manager and the Couatl Engine. Reply YES to both questions.
- TURN OFF your antivirus. Don't just exit from its interface, but turn off the real time protection. Actual wording changes between products, however, it's the option to scan every file that gets open in real time, without user intervention.
- Reinstall GSX with the Antivirus TURNED OFF. Don't launch FSX yet.
- Configure the antivirus to exclude the following files from scanning:
YourFSXFolder\bglmanx.dll
YourFSXFolder\fsdreamteam\Couatl\couatl.exe
YourFSXFolder it's usually C:\Program Files\Microsoft Games\Microsoft Flight Simulator X, if you installed it in the default folder.
- Now you can turn the antivirus back on, and launch FSX.
- Check you are seeing BOTH the "Addon Manager" menu AND the "Couatl powered products" menu under the "Addons" menu.