Hi Valachio,
I encountered the same roadblock as you and after digging through a few information here and there I was able to get through this. Hope this helps.
At the top "View" -> "Navigator" -> "Show Navigator" (Alternatively you can also open this using the shorthand ⌘+0)
Clicked on the root of the folder (which may be named for you as "Scrumdinger" with the app store icon on the left)
There will be "PROJECTS" and "TARGETS" click on the "Scrumdinger" at the "TARGETS"
There will be "Identity" row and there you will find your "Bundle Identifier"
Copy that (*********) whatever name it is there.
xcrun simctl get_app_container booted (com.example.apple-samplecode.Scrumdinger) data replace the ( ) to the (*********)
which will look like this "xcrun simctl get_app_container booted (*********) data"