I've recently installed the AIG mod. First, the reason I'm asking on the AVSIM forums is because my registration on the AIG forums still has not been approved.
I continue to get this error at every step: 

Your OCI installation is located in a directory that will come close to the maximum path-length of 255 characters!
To make sure AIM runs without issues it is suggested to move the OCI package somewhere else.
Use the Move-Option in the OCI settings to relocate the package and add a junction-link in your community directory so MSFS and AIM can detect the new OCI location without issues.

I cannot seem to find the Move-Option menu in settings, and I'm not sure if it's complaining about the directory I placed the installer in (B:\MSFS\AIG\AIG AI Manager) or my community folder, which I cannot change the location of (C:\Users\AAA A\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community)
Any help is greatly appreciated.

I used this video for reference, I had the same problem but cannot remember how now. Hopefully this will guide you.. 

I remember there is one point in the setup where you are asked if you want to install AIG to the default location. The default directory with a long pathname is already entered in the box, and it tells you "you must use this directory." You can, however, enter a new location with a much shorter pathname say D:\ and the setup will use that..

3 hours ago, dobee51 said:

I remember there is one point in the setup where you are asked if you want to install AIG to the default location. The default directory with a long pathname is already entered in the box, and it tells you "you must use this directory." You can, however, enter a new location with a much shorter pathname say D:\ and the setup will use that..

Is it possible to change the location later, or will I need to reinstall the whole app?

If you don't change it to another folder, I think you will keep getting that long file error. So I don't see any benefit in doing it later rather than sooner.