Integration between Shopify and Soisy Payment Gateway -- 2

Needs integration of Soisy Payment Gateway with Shopify. Customer will select a manual payment created from Shopify called Soisy, before order confirmation will start an API call with Soisy that will create an order and redirect on soisy portal. After Soisy flow ends, it will redirect on success or fail page on Shopify shop through callback. This is Soisy DOC https://doc.soisy.it/en/Introduction.html.

This is the suggested flow from Soisy:

There are four main sequential steps that are part of the Soisy's integration:

1 - Order creation
2 - Creation and approval of a payment request
3- Upload of the customer's documents ID
4- Digital signature

You can use our APIs untile the second step. After the first or second step, you can redirect your customers to our webapp and let them finish the remaining steps on our funnel.

We need, as suggested only to integrate first step (https://doc.soisy.it/en/Integration/Order/Create_an_order.html) so after that take the response and redirect user to soisy app and when Soisy flow finish, take user back to Shopify with correct success page and update order with paid informations.

Please bid only if you know what to do.

Thanks