add_action('woocommerce_single_product_summary', 'restrict_free_download_to_logged_in_users', 5);

function restrict_free_download_to_logged_in_users() {

global $product;

if ($product->get_price() == 0) { // Only for free products

if (!is_user_logged_in()) {

remove_action('woocommerce_single_product_summary', 'woocommerce_template_single_add_to_cart', 30); // Hide button

echo '<div class="woocommerce-info">Only registered users can download this free product.</div>';

}

}

}