@keino333 RealLight is never in the addons menu, so that's normal. This is likely because of conflicting files in the RealLight texture folder (could be from modifications, a partial update, etc.). The process to repair it is very simple, but can be a bit tedious to explain.
For anyone having the problem, these are the steps:
Go to your P3Dv4\SimObjects\Airplanes\TFDi_Design_717 folder
Delete the RealLight\Textures folder
Navigate to %localapptata%\TFDi Design Addon Manager\Downloads\13\
Open the "Asets_P3Dv4.X.X.X.X.zip" (that number will be whatever the latest is, at the time of writing, it is Assets_P3Dv22.214.171.124.0.zip)
Inside the zip file, find SimObjects\Airplanes\TFDi_Design_717\RealLight
Copy the Textures folder from inside the zip file to the location of the original deleted textures
Alternatively, a FULL reinstall of the aircraft will also do it (note: you MUST delete all leftover files per the Addon Manager's instructions for that to work).
If you'd like, we can setup a remote support session and I'll take care of it for you and you'll be up and running in no time.