Hi! I login to the game with my PlayFab username. After I'm entering a room created by Photon. My purose; When I enter the room, I want to see me and other users PlayFab Username or display name. What should I do?

For syncing players’ display names on the server executable, a possible idea is to let every client send a message contains their own display names to the sever, then let the server broadcast names to every client. You can call client API GetPlayerProfile to get the player’s display name after they logged in, properties those allow to be retrieved are configured in the Game Manager "Client Profile Options" tab in the "Settings" section. If you have some advanced questions about Photon servers, you can navigate to Photon forum for professional supports.