Code snippet to add the WooCommerce cart quantity and total to a SuperSide Me custom cart button.

woocommerce.php

<?php

add_filter( 'supersideme_custom_buttons', 'prefix_add_woocommerce_quantity_total_button' );
/**
 * Add the WooCommerce quantity and total to a shopping cart button.
 *
 * @param $buttons
 *
 * @return mixed
 */
function prefix_add_woocommerce_quantity_total_button( $buttons ) {
	// First, check to make sure WooCommerce is running--if not, stop.
	if ( ! function_exists( 'wc' ) ) {
		return $buttons;
	}
	// Cycle through all the custom buttons and add the custom Woo data to the cart button.
	foreach ( $buttons as $key => &$b ) {
		// Change 'Cart' to whatever your button label is.
		if ( 'Cart' === $b['label'] ) {
			global $woocommerce;
			$cart_contents_count = $woocommerce->cart->cart_contents_count;
			$cart_total          = $woocommerce->cart->get_cart_total();

			// Remove the conditional to always show the quantity of items and cost.
			if ( $cart_contents_count > 0 ) {
				$b['text'] = ' <span class="woo-cart">' . $cart_contents_count . ' (' . $cart_total . ')</span>';
			}
		}
	}

	return $buttons;
}