install is as usual... download the file, go to blender preferences/ add-ons / install... choose the file.

You can find the addon in the environment properties tab:

In the top menu, choose Sky settings or Studio settings.

Set your viewport shading to rendering (4th ball). Choose Eevee or Cycles button.

Customise the parameters , try the presets.

SKY:

Saturation is controlling environment color saturation only, not objects shading

Override replace the background procedural environment visibility by flat color without affecting lighting

Sun spin controls sun orientation

Sun Bend controls its sky position, up and down

Power is for lighting power and color is for... sun color

Sky is mapped with a gradient you can customize

Floor level push every colors up or down. Very cool to create lighting variations from unique setting (try it!)

Clouds are pretty basics but very important for reflection variations. It change a lot from clear sky to high cloud density.

Alpha is cloud transparency

Density is cloud dentisty

Motion can be animated for cloud motion but cool to try different still cloud aspects

5 presets to test

Easily bake you creation to HDR image. Just choose the resolution (1,2,4,8,16K) then click the button.

Save the render to HDR format. you can then import it for environment mapping with 100% matching result. Fast to bake because only enviroment is rendered

STUDIO:

Power is Master power, controls everything.

Floor mask is for Eevee Only. Eevee hdr lighting don't cast direct shadows so, if a light is under the floor, it create impossible lighting. this option block every lighting from under the floor level

Saturation is controlling environment color saturation only, not objects shading

Override replace the background procedural environment visibility by flat color without affecting lighting

 Spin controls horizontal orientation for the light panels

Bend just bend the spin axis so you can create lighting variations (try it!)

Light 1 and 2 have power and color controls

Ceilling is like the studio ceiling and floor, its floor.

They can emit colored light. cool to use it with low value to create subtil reflection on you objects shading (but do what you want!)

Room power controls both floor and ceiling power.

Easily bake you creation to HDR image. Just choose the resolution (1,2,4,8,16K) then click the button.

Save the render to HDR format. you can then import it for environment mapping with 100% matching result. Fast to bake because only enviroment is rendered

:: enjoy