You do not have to activate plugins because all plugins are bundled. It is common way of adding plugins in the Themeforest Themes. You can read more about it in the official article from Themeforest: https://help.market.envato.com/hc/en-us/articles/213762463-Bundled-Plugins
The main part: "Some plugins may ask for a purchase code for registration/activation once installed, however, you can simply ignore these messages as bundled plugins do not require activation or registration. The plugin will still work as intended with the theme once the theme has been activated/registered. "