Edit and test themes on local device

[Trantec]

The store already exists and ist live.

I want to improve my workflow by editing and testing theme changes on my local device, instead of editing code in the webbrowser via admin.shopify portal.

As I understand that Shopify CLI is the way to go.

Everything that is needed is installed, when I execute "shopify theme pull --store *******.myshopify.com" the message "You are not authorized to use the CLI to develop in the provided store." appears. But I am the owner.

Do I need to register as a shopify partner for that? The problem there is, I am not able to add my shop there, because the partner and owner is the same account.

Maybe I misunderstand the whole Shopify CLI thing?