Fatal error: Uncaught Error: Class ‘WOOMULTI_CURRENCY_Data’ not found

hello i need urgent help plz
im using your plugin and on add to cart im trying to change the price to different currency but before doing that i was trying to fetch data and im getting error undefined class plz tell me what is wrong.

here is my code

add_action('woocommerce_before_calculate_totals', 'convert_cart_prices_to_ron');
function convert_cart_prices_to_ron($cart) {
    if (is_admin() && !defined('DOING_AJAX')) return;

    $selected_currency = get_woocommerce_currency();
    $conversion_rate = 1;

    if ($selected_currency != 'RON') {
        $currentCurrencyRate = 1;
        if(class_exists('WOOMULTI_CURRENCY_Data')) {
          $multiCurrencySettings = WOOMULTI_CURRENCY_Data::get_ins();
          $wmcCurrencies = $multiCurrencySettings->get_list_currencies();

          $currentCurrency = $multiCurrencySettings->get_current_currency();
          $currentCurrencyRate = floatval( $wmcCurrencies[ $currentCurrency ]['rate'] );

        }
    }

    foreach ($cart->get_cart() as $cart_item) {
        $price = $cart_item['data']->get_price();
        $cart_item['data']->set_price($price / $conversion_rate);
    }
}