Failed to open stream on new installation of Sage 9

Hi,

I have some problems installing the new Sage 9 theme. I run composer start-project roots/sage example dev-master, then activate a theme in the WP Dashboard. This is what I get:

I don’t have a uploads directory or any of the directories following it.

I have not touched any of the files. My dev environment is XAMPP.

Any ideas?

Thanks!