Just append the nodegroup from the purchased blend file.

The simple nodesetup is called "Studio HDRI simple" and the advanced is called "Studio HDRI".

Apart from the description on the product page, the advanced setup offers more control on the lightpanels 2 and 3. They share their brightness, softness and size independent from the panel 1.

The rest is as simple as seen on the product page:

• set the base light 
  

• span the colorspace by pushing color range from the base color to its complementary color

• color bend is shifting the color range for panel 2 and 3 away from the complementary axis

• set the brightness, sizes, softness and anisotropy of the panels

• create blinds if wanted, the blinds seed is a smooth evolution of the distribution of blinds. You can adjust it slowly if you almost like the distribution or strong, if you need something completely different

• transparency color and factor is additional light for the refractive shaders, to underline glass materials. This is very useful for liquor, bottle and glass shots

• floor can be set with color and size, to block reflections on the bottom of your model

• BG color acts as wall paint for the stuido walls, in which the panels are placed

• DOF is the depth of field blur for the background. Use it to get a calm gradient around your model, but keep crisp and sharp reflections. This is a fake blur, high values lead to fuzzy shading. increase render samples to avoid that.

• chromatic dispersion bends the colors hue in the refractive shading of the background. This can help to vitalize your monochrome parts of the shot quickly