Can't redirect to confirmation_url

[Mar123456]

Hello there,

I'm trying to test subscriptions in my Shopify test app. I'm successful with my GraphQL request:

result = ShopifyAPI::GraphQL.client.query(query)

The next step is the redirection:

fullpage_redirect_to result.data.app_subscription_create.confirmation_url

Unfortunately, on the front end I am getting redirected to the login screen, like on the image below:

 

Why is that? How to prevent from being redirected to the login page? Fun fact: If I go back to my test app, subscription is activated.