Magpie is using deprecated shaders in its configs. Luckily you can fix this manually with a text editor that has a find all/replace all function. VS Code works great for me, you can add the whole Magpie folder and it'll go through every files.
For the fix, find every "SSTU/PBR/Metallic" (without quotes) and replace with "TU/Metallic", do that again with "SSTU/PBR/StockMetallicBumped" replace with "TU/Metallic".