How to connect a subdomain of an existing Shopify store to a custom app? Now getting 301.

[ferencik]

Hi, I have a simple script that reads out the Shopify products under my account. But when I run it, I get a 403 forbidden error.

I read that I need to connect my domain to the Shopify admin, but I don’t want to use the live store URL. Instead, I want to use a subdomain of an existing store that is not yet live.

For example, if my store URL is shopify.com/store123, and my subdomain is dev.store123.com, how can I connect it to the Shopify admin?

I also created a custom app with almost all the credentials available. But I think there might be something missing.

Can anyone help me with this