To make sure all content gets installed properly, unzip the files directly to your DAZ Studio library.
For example: "DAZ Studio/My Library" or "DAZ Studio/Content"
1 Load Genesis 8 Male.
2 Go to People -> Genesis 8 Male-> Clothing -> JMR dForce Matteo Underwear.
3 Load the clothing by double-clicking on the outfit parts.
4 Material Presets are located in "Iray Materials" within the outfit parent directory.