Before starting, please check your server must have new/latest PHP version. Lower version of PHP, may cause of several errors and warning. Please upgrade it.
Step 1: Download the theme from themeforest and unzip it. You will find some folders like (‘documentation’, ‘resources’,’licence’ etc) and theme “.zip file” this is you actual theme to be installed.
Step 2: Install a new/fresh setup (latest version) of WP.
Step 3: Install the theme & all plugins. Activate the theme by entering your purchase code.
Step 4: Go to Admin -> Appearance -> Theme Options -> Demo Importer and run the importer.
You will get 100% working website in just few minutes.
For more: Themes & Templates