Thank you for the prompt reply and also the workaround. I assume that, although the property appears to be internal, we are allowed to submit the app using this?

Thank you for the prompt reply. I wrote this post because the template list missed the StoreKit configuration template (I also used the search field). Strangely, now after opening the beta again, it is available. At that time, I also had the previous XCode version open, and maybe this led to a hiccup. I don't know what it was, but now the template is available. Thank you.

Did you check that the "Allow Apps to Request to Track" switch is on, on your iOS 15 device?

They renamed it to Add Packages and put it directly under File. Here is also a help article from Apple: https://help.apple.com/xcode/mac/11.4/index.html?localePath=en.lproj#/devb83d64851