I just recently got a new computer with Windows 11. The base Diablo games work, but all of the mods says that I don't have the file "msvcp100.dll". But I found it so I definitely have it. How do I get the mods to see this file to work?

Not true DevilutionX doesn't require this dll... in fact I think it's probably only very few mods that do. Maybe you can be more specific?

As far as I know the prefered method should be to install the Visual Studio 2010 Runtime, which can be found on Microsoft's website here: https://learn.microsoft.com/en-US/cpp/windows/latest-supported-vc-redist?view=msvc-170#visual-studio-2010-vc-100-sp1-no-longer-supported

You could also try just adding the folder where that file is to your PATH environment variable, if it's not in there already.

Looks like this could be an a requirement for running Belzebub so if that is the one you are having issues with then I think Constance's suggestion is the right solution.

Thanks everyone. I will be trying that stuff.