Reviewer Recruiters are the people that accept or deny reviewers. A list of them can be found here.
Currently, to become a recruiter, there must be less than around 7, and you must have been an active recruiter for a few months, and be commenting on reviewer applications, giving feedback. You must have also never broken a rule in the reviewer lane. If the above criteria fits, you can message the head of reviewer recruitment, currently epico, and ask to become a recruiter.