Hello and welcome to the community. I hope you’re well today! 
The most common cause of this issue is interference from security programs, such as anti-viruses.
It could also be due to an outdated or corrupted version of .NET Framework, which WeMod requires in order to work.
This thread here has some additional troubleshooting steps: "Wemod failed loading the cheats into your game" / "We’re having trouble downloading the cheats" - #2 by Ravenfyre.
If that does not resolve anything:
- Attempt to use a trainer in a game until it fails.
- Go to your settings by clicking the cog wheel in the top corner.
- There is an option in there to download a log. Do so and share it with us here.
Thank you!