Give access Smart Slider for non-admin users (WordPress)

To be able to allow your non-admin user groups to access Smart Slider you will need a plugin that is capable of handling the user capabilities, for example, the User Role Editor:
Go to it's settings (WordPress menu: Users → User Role Editor), then look for the capabilities that are named something like SmartSlider and Nextend:

Select them and save the capabilities for the user group.