I've use this Mod daily any never had any issue with it. I do have content manager. The Mod itself includes the line the the AI uses to run on the track. You still need to physically add the cars yourself for the mod to work. If you're using content manager:
Drive>Single>Track Day>Press the "+" on the opponents tray and select the cars you want to have on the map. Once you get all the cars in, run the map using the Shibauru PA traffic Map, or the Tatsumi PA traffic map. It will indicate 10 minute load time. Once you have all the cars selected for your opponents, you should be able to run the game with AI now.
Hopefully this helped with people having issues. This mod is great and definitely works once you've done everything right.