kann meinen Gameaccount bei der ESL nicht eintragen

In den Regeln steht dazu etwas nützliches:

Quote

4.1. Gameaccount

Every player has to have a valid gameaccount (SteamID DoW II: R)
entered in his profile in order to play in the European Dawn of War II:
Retribution section.

An easy way to get the SteamID of your account is to use Steam ID Finder.
You can enter a player's SteamID there as well to display the player's
account. This is can be useful to add him/her as friend for example.

Valid entries have the form "Y:Z:X". Y and Z are either 0 or 1 and X is an integer, the amount of digits X has are not fixed.