In your WordPress dashboard, go to Plugins > Add New (or Appearance > Themes > Add New).
Click the "Upload Plugin" (or "Upload Theme") button at the top.
Select the .zip file you downloaded from GPLClub.
Click Install Now and then Activate.
⚠️ Common Error: "The style.css file is missing" If you get this error when trying to install a theme, it means you uploaded the complete download package instead of the installable file. Solution: Extract the .zip file you downloaded. Inside you'll find documentation folders and another .zip file (the installable one). Upload that inner file.