Hi MinhDNguyen By Default, unless you change it to main, the default publish branch will be Workplace_Publish. In part 1 I left this as the default, but you can change it, even after deployment.
In the Management Blade you would click on Git Configuration, then click at the Gear icon at the top and it will open a blade on the right hand screen. you can change workplace publish to main.
Other wise every time you publish your JSON in Azure DevOps, it will publish the newest JSON to that Workplace_Publish branch. You would need to build off of that branch instead of main. It's get's a bit confusing to me, but my Buddy Steve St. Jean (to whom I owe teaching me how to do this prior to Winter Break in December) who is one of the best Developers I've ever met, assured me this was the way to go. And if I got any of this wrong, it is my fault and not Steve's, I'm just doing a bad job re-explaining this :).