role "my_account" does not exist

Hello!

Following this web page, I have tried to create a new role/user, but to no avail.

After typing the following command : createuser --interactive --pwprompt I get the following questions:

Enter name of role to add: company_name
Enter password for new role: xxxxxxx
Enter it again: xxxxxxx
Shall the new role be a superuser? (y/n) y

Than this error is displayed :
createuser: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432"
failed: FATAL:  role "my_debian_login_account_name" does not exist

However, this issue is not really relevant, per se, since I am able to create roles once I log in PostgreSQL-15. Nonetheless, if the service exist, why not usu it. If the services exist and is not working, could it be that there is a problem that will come apparent later on, when unlike now, it would be during a critical moment. Thus the question, what can I do to resolve this issue?
Is there something I am missing?

Thanks