To configure a control repository on a Puppet Enterprise instance, you will need to provide the SSH URL to your Puppet control repository. Make sure your branch is not called production as that will interfere with the PE intance's master servers.
The puppet-git user will need Reporter access to you control repositories. Generally, we recommend that you create a 'puppet' subgroup in GitLab, grant Reporter access to puppet-git on the subgroup and then put all of your modules/control repositories into that subgroup. It is also recommended to separate control repositories and place modules in separate repositories and then enumerate them all in the Puppetfile.
If you don't have a control repository, please see https://its.uiowa.edu/gitlab for instructions on how to set one up.