Hello. 
Do you have the game from Uplay or Uplay+?
- If you have the Uplay+ version, you need to be using this trainer: Watch Dogs 2 (Uplay+) Cheats and Trainer for Uplay.
- If your copy of the game is cracked or pirated (which it shouldn’t be since WD2 was given away for free very recently by Uplay), then it needs to be expected that no trainer will ever work on it.
At the moment, I’m not sure what else to say. Nobody else has reported the same issue with the money cheat since this thread began. Are you sure you have entered the launch parameter correctly? Maybe provide a screenshot of it so we can see?
Regarding that message you got - Trainers do not work online so no, it makes no difference.