How to get permission of pushing ceph-ci

According to this doc(https://docs.ceph.com/docs/master/dev/developer_guide/running-tests-using-te...), I have got Sepia lab access. However when I push a branch to ceph-ci, I got 403. I have searched documents but got nothing about how this problem. By the way, the way to create the label likes "wip-username-testing" in ceph repo also confuse me.