Please follow the installation steps written in the documentation https://texstudiodoc.readthedocs.io/en/latest/3.install/

Decals like DECAL Machine, Fluent Materializer, or Sanctus Library are supported inside the texturing scene. And you can use them as you would normally do :)

TexStudio is isolating your object, but you are still in the main scene. If you move, rotate or scale your object, it will affect it in the main scene. Prefer scale, rotate or move the studio instead.

If you have a favorite light set or studio you like, you can import it into TexStudio to have it ready in a few clicks in all of your projects. See the documentation for more details https://texstudiodoc.readthedocs.io/en/latest/7.create_studio/ 

Some studios or light sets might not be working with Eevee. If you get studios and light sets from other creators, make sure to ask them.

As for the included studios and light sets, here is the list of studios and light sets that are not working well with Eevee:

- Materializer studio

- Forest Shadows lights

- Window Light

TexStudio is importing a studio and a light set, you can then use Blender as you normally do.