How to execute post-receive git hook on All-Users repo

I have added the post-receive hook onto the server, and when I manually push to the repo it works as expected. I am looking to execute a post-receive hook when a user signs up and refs/meta/external-ids is updated. I have confirmed that this hook is not executed when a user signs up, similarly it is not execute when a user is added through REST endpoint. I'm not sure if the gerrit hooks plugin will accomplish this task either