If you are running dgraph alpha service on the vulture system, then you would use the that as the node:
dgraph cert -n $HOST_ADDRESS
Where host address is the dgraph alpha service. If you build a server for example and give it a DNS FQDN of dgraph.mycompany.com, you would then do this:
dgraph cert -n dgraph.mycompany.com
Until then, it looks like you are running the server on MacBook, and a client on MacBook, so you have to use localhost as the host address in this case for local MacBook development.
As for Brave (Chromium) browser, you need to import the client certificate, so that it will trust use the Dgraph CA root.