This appears to be a bug: the development team listed in the error message is the one used by Audiokinetic for development on the Mac platform and should not be present in projects generated by wp.py.
I will enter this bug in our system.
As a workaround, you can open the Xcode workspace generated by the wp.py premake command (PluginName_Mac.xcworkspace) and change the Development Team in the Build Settings section to an empty string.
To do that, for each column, click on the combobox and select "Other", then clear out the value and press Enter. Do that for both projects (the _shared and _static as selected on the left sidebar), and you should be able to build without error.
To ship your plug-in, it will eventually need to be signed and thus will require setting a valid development team, which you obtain from an Apple developer account.
For now, happy coding!