Deep Theme has many plugins included, which can save you from hours of searching online for the proper options for your needs.
After activating the theme, please head over to the theme Dashboard, in the sidebar menu. To install the plugins navigate to WordPress Dashboard > Deep > Plugins. then click on install, then on activate.
After installing the theme, you can activate any plugins you need.
Also, you can access the plugins from this panel at any time. Here you have the options to install, activate, and deactivate plugins. You can also access the plugins by navigating to WordPress Dashboard > Plugins.
One more thing, If you want to install new plugins (not the ones that are included in the theme) you need to go to WordPress Dashboard > Plugins > Add New.Managing Plugins