Enabling "Mirror" repository checkbox in CE v11.10.2

We have been using Gitlab v10.7.2 (CE) version for about an year now. We recently upgraded to v11.10.2.
The features that was of interest was:

https://docs.gitlab.com/ee/user/project/import/repo_by_url.html#import-project-from-repo-by-url

We want to mirror the repositories of interest and periodically update (pull) from the repositories we have created projects locally. However we are not able to view the “Mirror” repository checkbox.

Any clues ?

Warm Regards,

Raghunandan