Hello and welcome to the community. 
First of all, make sure you are using the correct trainer.
- For State of Decay 2, you need to use this trainer - State of Decay 2 Cheats and Trainer for Windows Store
- For State of Decay 2: Juggernaut Edition, you need to use this trainer - State of Decay 2 (Juggernaut Edition) Cheats and Trainer for Windows Store
If you are using the correct trainer, click History (under the Play button) and make sure you are using the most recent, up-to-date trainer by clicking the one in the top of the history list.
If you’re still having trouble, see this post here: State of Decay 2 (Juggernaut Edition) Cheats and Trainer for Windows Store