Push gitlab repo to bitbucket

I am working on a project for a client. We currently run our own gitlab internal servers. The client wants us to push our code into their bitbucket repo. I would like to create a Mirrored Repo with just push direction. So we develop our stuff internally, but when we commit our changes that should trigger a push to the clients bitbucket account. I have got to the setting → Repository → Mirroring repositories. There I added my repo URL and put my password in there. When I attempt to sync I get an error “Incorrect login creds” (But I know I am putting the correct creds in.) What am I missing?