Edited: Incorrect fix, see "Sunnhild" 's reply for correct fix:

I found a solution for directional light shadow:

in shell's Lit.hlsl

From Line 120 to Line 123 (the author's file)

```( this is line 119 )
float4 color = UniversalFragmentPBR(inputData, surfaceData);

ApplyRimLight(color.rgb, input.positionWS, viewDirWS, normalWS);
color.rgb += _AmbientColor;
```( this is line 124 )

Change it to:

```( this is line 119 )
Light mainLight = GetMainLight(TransformWorldToShadowCoord(input.positionWS));
float shadow = mainLight.distanceAttenuation * mainLight.shadowAttenuation;
float4 color = UniversalFragmentPBR(inputData, surfaceData);

color.rgb *= shadow;
ApplyRimLight(color.rgb, input.positionWS, viewDirWS, normalWS);
color.rgb += _AmbientColor;
```( this is line 127 )

Don't know if it is correct, but it works. ( I cannot write shader code )
Please feel free to correct me!

After adding the code, you will have this result:

Terrible self-shadow ( can be fixed )