The ansible roles are not resident in this repository. They must be pulled from other repositories. To do that, run the following command inside the roles directory
$ ansible-galaxy install -r ./install_roles.yml -p .
If you would like to make any changes to a role, do not do it here. Make any role changes in the role's own repo. Then, erase the role's directory here and rerun the ansible-galaxy command to pull a new copy.
Directories other than the roles directory contains a vagrantfile and a playbook. The vagrantfile uses the playbook as its provisioner. See the README.md in each subdirectory for details.