Not able to intall this plugin

Hello
I am not able to activate the plugin after installation.
It gives me the following error:
Call to undefined function WC() in /home/xyz/public_html/wp-content/plugins/woocommerce-pay-for-payment/admin/class-pay4pay-admin.php on line 98

Please help me.

https://wordpress.org/plugins/woocommerce-pay-for-payment/