Okay, for all those who have spent hours and days looking for a solution : here is my finding :
What will make the difference between you playing the game and having fun AND you sincerely thinking about killing yourself in a blood ritual , there are only damned <SPACES> in the file you create !
So here is the way you must write it (Be extreeeeeemely careful with spaces after the "Elevated:" part !) :
# Admin Configuration
# This file can contain two lists: one with elevated players with special permissions
# and one with banned players.
# 'Id' is a SteamID64 in both lists, lookup possible at https://steamid.io/
# 'Permission' is 3 for 'GameMaster', 6 for 'Moderator' and 9 for 'Admin' - other values are not allowed.
# 'Until' is the time when the ban ends.