pg Admin 4 - password for "postgres" user when trying to connect to PostgreSQL 13 server

I know that this question has been asked other times but I didn't find a solution to this problem!

I downloaded PostgreSQL 13 with pg Admin 4 and when I open it for the first time after installation it asks me for the master password that I was asked to set during installation, after I give the master password and this gets accepted I try to connect to the default server created during the installation: "PostgreSQL 13".

At this point, it asks me for a password for the user "postgres" that I don't know where to find. Specifically, it says: Please enter the password for the user 'postgres' to connect the server - "PostgreSQL 13".

I've already tried all the "default" passwords I managed to find on the internet but the error is always the same:

FATAL: password authentication failed for user "postgres"

I've also tried not to insert any password with the resulting error:

fe_sendauth: no password supplied

I don't know what to do. In PostgreSQL 13 the authentication method is encrypted via scram-sha-256. I already tried to set the method to trust, restart the mac, and open pg Admin 4 that keeps asking me for the password to access the server.

I've also tried to use the command line tool but end up encountering the same errors.

Finally, this is how my pg_hba.conf looks like:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     scram-sha-256
# IPv4 local connections:
host    all             all             127.0.0.1/32            scram-sha-256
# IPv6 local connections:
host    all             all             ::1/128                 scram-sha-256
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     scram-sha-256
host    replication     all             127.0.0.1/32            scram-sha-256
host    replication     all             ::1/128                 scram-sha-256

PS. I've also tried to uninstall PostgreSQL 13, deleting the postgres user and re-download and re-install everything... nothing changed.

If someone could help me would become my savior, thanks beforehand!