Tournament admins and every tournament participant can see the matches in the referee panel. However, admin can share the referee code to any Rankedin user, and using that code, the match can be refereed.
Referee codes for all matches from the tournament can be found in the tournament admin panel in step “8.Matches” by clicking “Referee codes(1)” button. Admin can share these “Codes(2)” with any Rankedin user.
When you have the referee code, just open the referee panel by clicking “E-Referee(1)” in the top bar
In the referee panel, select “Code(1)”,paste the code(2) and click “Go”.
Check how to referee match(Link)