Setup on Windows (metacello error)

[thewrath]

Hello, I'm trying to set up this project on Windows but I'm getting a conflict error when I try to retrieve the project with Metacello:

Have you already encountered this error? I have a Pharo 9 image.

I don't know if it's possible to run this application on Windows with another backend than GTK3? I'd like to test this project to get an example of using Spec.

Thanks