Why does the playbook fail?

Make sure that you are on ansible version >=2.1. You can check your ansible version by typing:

ansible --version

What is the username and password of the galaxy admin account ?

Username and password of the galaxy account are controlled by the variables galaxy_admin and galaxy_admin_pw and default to admin@galaxy.org and admin (Defaults are defined in group_vars/all). This should be changed in the group or host variables for the host you are working on. If you have a host in the mygroup group, you can edit group_vars/my_group and set

galaxy_admin: new_admin@email.com
galaxy_admin_pw: new_password

As with each change, run the playbook again.

How can I set up GalaxyKickStart behind a proxy?

Many commandline utilities can be configured to use a proxy by setting the http_proxy and https_proxy environment variables. Tasks launched by ansible will only see these environment variables if ansible sets these variables for the task. We have included a global proxy_env variable in the galaxy.yml playbook. You can set the content of this variable in your inventory or group variables (See Customizing the playbook for details on how to define variable). To use the proxy at http://proxy.bos.example.com:8080 define the variable proxy_env like so:

proxy_env:
  http_proxy: http://proxy.bos.example.com:8080
  https_proxy: http://proxy.bos.example.com:8080
  no_proxy: localhost,127.0.0.0,127.0.1.1,127.0.1.1,local.home

Adresses that should not be contacted through a proxy should be listed in the no_proxy variable. An example can be found in group_vars/proxy.