The developer of this trainer is retired from WeMod, therefore it is likely out of date.
Make sure that you are selecting @MrAntiFun’s trainer for this game in the WeMod desktop app, not the one by STN.
Community thread for MrAntiFun’s trainer: Two Point Hospital Cheats and Trainer for Steam.
Thank you. 
This thread will be locked so that this post doesn’t get buried.