If you mean FSDT KLAX, which I guess it's the case here, the scenery comes with its own AFCAD, which is installed automatically under the fsdreamteam\KLAX\scenery folder so, unless you removed something manually, you surely have it.
If you don't have it anymore, just run the KLAX installer again, which will restore any files that might have been removed for any reason.
You should NOT use a downloaded AFCAD, unless it's made SPECIFICALLY for FSDT KLAX, and even in that case, it must be named like the FSDT one, and placed in the fsdreamteam\KLAX\scenery folder, otherwise you'll lose the FSDT-provided GSX customization for it.
