Connect to Robokassa website to WordPress

Need on the website (Wordpress) to connect a payment system Robokassa, by pressing the button.

WooCommerce is not installed. The contract with Robokassa concluded.

1. To connect the 2 products. joxi.ru/Drlvb4yuVJoqO2
To do so in the future when you add a new subscription it was possible to connect the payment.

2. After purchasing the subscription, the customer on his e-mail comes the receipt.
Us information about the order must come in the mail.

3. Mandatory information to be filled in by the customer, upon purchase: name, phone, email.mail.