You are using staging server - a separate instance of the ESP Component Registry that allows you to try distribution tools and processes without affecting the real registry.
To create a project from this example, run:
idf.py create-project-from-example "test_component_manager/test_c8510416-7d6b-419d-b47f-d972b0ecd374_yankable=1.0.0:cmp_ex"