To be able to log in to your new server you need an account.
It is recommended to use security level 3 for your own account.
account create <user> <pass>
account set gmlevel <user> <level> <realm> (-1 all realms)
account set password <user> <password> <password>
The highest security level is SEC_CONSOLE (4) which your worldserver has by default.
It has access to account management and is not recommended for in-game accounts for anyone that does not know what they are doing.
To update an account to security level 4 you need to manually edit the fields in the database or run the query below.
UPDATE account_access AS access INNER JOIN account AS account ON access.id = account.id SET gmlevel = 4 WHERE username = '<user>';