Some developers have attempted to repackage UWP apps as standalone executables (.exe), though these are often unstable and carry security risks.
Paint 3D uses DirectX 12 features that aren't fully supported in the Windows 7 environment. download paint 3d for windows 7 ultimate
Windows 7 lacks the framework to run .Appx files used by Paint 3D. Some developers have attempted to repackage UWP apps
Find a for a safe alternative like Paint.NET and a massive library of plugins.
If you want the creative power of Paint 3D without the headache of OS compatibility issues, these programs are your best bet:
Walk you through to run Windows 10 apps
The gold standard for Windows 7. It supports layers, transparency, and a massive library of plugins.