While it’s not a good idea to modify plugin code directly, in this case changing the file class-text-slider-admin.php (in the admin folder) on line 453 from 'manage_options'
to 'edit_others_posts'
will allow users with that capability to see the Text Slider menu item. That means Editors can access it. If you want other User Roles to have access, you’d need to use a different capability.
To be clear, the entire function should now look like:
public function add_plugin_admin_menu() {
$this->plugin_screen_hook_suffix = add_menu_page(
__( 'Text Slider', $this->plugin_slug ),
__( 'Text Slider', $this->plugin_slug ),
'edit_others_posts',
$this->plugin_slug,
array( $this, 'display_plugin_admin_page' ),
plugins_url( '/assets/images/slider-icon.png', __FILE__ )
);
}