I have a quick fix: As the error says, Psychopy is looking for the prefs variable useRunner. The variable is not set in your userPrefs and you cannot set it through the builder interface for now. You can, however, go to your preference file userPrefs.cfg, which will be in a folder like %APPDATA%psychopy3 on Windows and ~/.psychopy3 on Linux/MacOS and create an entry for useRunner there.
In this file, add the line useRunner = False somewhere under this heading:
# General settings
[general]