Shopify BASIC plan integration costs with external backoffice

Hello,

I have a customer that has a Shopify store with BASIC plan and he needs to integrate it with his Backoffice app.

I have created a Shopify demo store to test the integration and after some tests, I was able to integrate it successfully with an external app.

My question is: the customer current BASIC Store plan already includes integration with external systems or he needs to pay additional fees or upgrade to Shopify / Advanced plans?