Unzip and upload `wupo-group-attributes-pro` to the `/wp-content/plugins/` directory or choose the zip archive in the admin backend from Plugins -> Add New
Activate the plugin through the ‘Plugins’ menu in WordPress
Open the settings page of the plugin with a click on 'Settings' from the plugin overview page. Alternatively go to WooCommerce -> Settings -> Group Attributes
Make sure the checkbox 'Enable Group Attributes' is selected and save the settings