Writing to a google sheet using sheet.best

I asked this question as a reply on this thread but it seems inactive so I’m posting it as a new question, the first post on the original thread is all you need for context.

Hi, bubble noob here hoping someone could help. I’m getting a little stuck on step 10 onwards, my body looks like this.

{
   "branch": [
	
      {
         "branchName":"<branchName1>",
         "branchCount": "<branchCount1>"
      },
	
      {
         "branchName":"<branchName2>",
         "branchCount": "<branchCount2>"
      }
   ]
}

When I click initialize call my near empty google sheet appears regardless of what I put in as the value of the , etc. Is that meant to happen?
Should I manually put in values for the dynamic data or leave it empty?
When you say tag items as exported, does it mean I have to add a new yes/no field to my branch datatype?
How do you access sheet.best from the backend workflow like they did in the image?