You need 3.1 desktop runtime:
dotnet.microsoft.com/en-us/download/dotnet/thank-you/runtime-desktop-3.1.30-windows-x64-installer
dotnet.microsoft.com/en-us/download/dotnet/thank-you/runtime-desktop-3.1.30-windows-x86-installer
Thank you so much for help! I got the Trainer to work, and tested a bit with Divinity OS 2. I think I have needed exclusions set in Windows Security on Windows 11, but am missing the exclusion for the .tmp file ~mnn or something? Is it needed for all Trainers? I tried to search for it when I had the Divinity OS 2 Trainer running, but was unable to find said file. Further help appreciated 🙂