Hello and welcome to the community. 
The most common causes of this error are:
- Interference from a security program on the PC or network.
- Incorrect file path in the trainer (ie, due to the game being on a different drive).
- Outdated or corrupt .NET Framework - Windows Updates frequently forgets to install, upgrade, or fix .NET issues.
This thread may be of help and covers the above, plus more: "Wemod failed loading the cheats into your game" / "We’re having trouble downloading the cheats" - #2 by Ravenfyre.