Follow these steps:
Create a folder on your preferred drive, for this example we will use D:\ but you can use any drive letter. Create a directory with the name Prepar3D Addons
Inside create another folder with the name Custom AI Models
Now Move all your customs AI Models to this folder, leaving your default airplanes, etc. inside P3D.
Create a folder inside C:\Users\YourName\Documents\Prepar3D v4 Add-ons with the name Custom AI Models
Create a new file