Start Greyscalegorilla Studio browse for any 3D model you would like to use and click the download button on the thumbnail.
When download finished you will see "Send" button. Click it to send the 3D model to Content Browser.
Now you will green check mark indicating that the transfer is successful and the 3D model is added to Content Browser. It will be listed under Greyscalegorilla > Models folder.
You can drag the downloaded 3D model from Content Browser to Viewport.
Then click your Greyscalegorilla > Materials folder on the Content Browser and assign a material by dragging onto model.
The material will be applied to your model instantly.