We never store passwords in any Couchbase cluster. Therefore, it is not possible to migrate the users along with their passwords and roles to another cluster.
We are currently working on a feature for our next release using which you will be able to import/export the users along with their roles.
Currently, you could list and create users and roles using the REST interface. But the users’ passwords will have to be manually set in the request.
You can also refer to the similar solution suggested here: Users backup and restore