Error for undefined method WC_Order::get_status()

Hi, I’m installing and configuring the plugin for italian gateway UniCredit but at the first test I have received this error
Fatal error: Call to undefined method WC_Order::get_status() in /web/htdocs/www.biodomusroma.it/home/wp-content/plugins/big-fish-payment-gateway-for-woocommerce/big_fish_payment_gateway.php on line 554

Any idea what’is it for?

Thanks in advance.

https://www.ads-software.com/plugins/big-fish-payment-gateway-for-woocommerce/