Plutonium.zip -

%localappdata%\FoundryVTT\Data\modules\plutonium .

Download the .exe directly from the Plutonium site rather than unverified .zip files from forums. Plutonium.zip

Extract the contents to your Foundry Data/modules/plutonium folder. %localappdata%\FoundryVTT\Data\modules\plutonium

Be cautious with files named Plutonium.zip found on file-sharing sites or YouTube descriptions. Plutonium.zip

Only download from official project sites like plutonium.pw or trusted community wikis.