Do you have both the Addon Manager and the Couatl menu under the GSX "Addons" menu ? If no, the problem of missing menu items under the Addons menu it's usually caused by one of these:
1) Defective antivirus. Download and install with the Antivirus disabled AND configure the antivirus to exclude the whole Addon Manager folder from scanning BEFORE starting the sim.
OR
2) Missing/Corrupted VC++ libraries in your system. See solution in the "Addon Manager not showing up in P3Dv4 **SOLVED**" thread:
http://www.fsdreamteam.com/forum/index.php/topic,17484.msg122656.html#msg122656