These instructions are a bit scant for a first time Xcode user. I haven’t used it in many years, so here’s what I had to do. Using the current Xcode beta — Version 13.2 beta 2 (13C5081f).
Open the project.xcworkspace file to open the Blackhole project window.
Add your developer account login details to Xcode, goto Xcode Menu> Preferences… ( the second tab of Xcode prefs). Add account(s) for code signing.
As above, click on the root level container of the Blackhole project in the left-hand sidebar to show the tabs, then click on the Signing and Capabilities tab.
You can copy each line of source code and use Find to highlight it in code then copy the replacing line and paste that over it.
Just restarted… it worked.