Not able to configure the Shopify Theme App Extension with latest version of Laravel Shopify package

[prashantk3]

@Kyon147,
I need to setup the Theme app extension as per Shopify recommendation. I already followed the steps as mentioned on https://github.com/gnikyt/laravel-shopify/wiki/How-to-create-App-Extension . But unfortunately i am not able to create the Theme App Extension and i am getting the message as attached screen

and when i tried to open the partner link manually i am getting the error "127.0.0.1 refused to connect.", also attached the screen for the error.

Please suggest how to configure the new Theme App Extension with an Existing Shopify Non-Embedded App. Please help.