Our Gitlab instance does not allow any user to fork or create snippets, this creates issues with contributions that can be solved by using this system until we have a better solution, we very much appreciate anyone that wants to contribute, our server resources are limited and developer time is also limited to deal with spam and fake accounts.
After some time if you contribute often and are trusted by the team we can provide fork access until then this method also works if contributors are willing.
Before you clone and make any kind of changes, talk about what changes you want to do in a issue if those changes are accepted, then go to your Github account and under repositories click new.
On the very top chose import a repository.
Head to https://gitlab.manjaro.org/repo-name and copy paste the address in URL field and click begin import, it should take a few minutes depending of the repository size.
After that is done, all you need to do is open a new branch on Github and make your changes, then on the issue on you opened on manjaro Gitlab link the branch with your code, after that a manjaro developer will pull that branch to Gitlab and test the code.