Step 1 - Logging In
Login to your App Builder account and use your Shopify URL to verify your credential.
Once you're logged in, head to the 'My Account' section in the top right corner.
Step 2 - My Account
From the My Account screen, select 'Store Information'.
Once you've highlighted Store Information, enter your Shopify URL in the field and select 'Link Directly with Shopify'.
Step 3 - Authorizing Through Shopify
Once you select Link Directly with Shopify, you will be redirected to the Shopify Dashboard.
Click 'Update Sales Channel' to authorize Sandbox Commerce's permission requests. This will allow the App Builder to access your inventory and store information.
Step 4 - You Did It!
Congrats! You've successfully connected your Shopify store to the Sandbox App Builder.