Here is a quick video tutorial that shows you exactly how to add admins to your server on PS4!
https://www.youtube.com/watch?v=5C9siylHv9M
In order to open the menu you saw in the video do the following!
Open up your settings while joined in your PS4 server.
Press L1 + R1 + Square + Triangle to open the Request Admin toggle. Type in your password and Request Access. Type in the commands below, found here: https://survivalservers.com/wiki/index.php?title=ARK_PS4_Admin_Commands
Hope it helps!