This error message and behavior are because of a problem with pgpool authenticating to postgres, not with you authenticating to pgpool as you might suspect. If you check the postgres logs, it will tell you which line in your postgres pg_hba.conf
is being rejected.
However, since (IIRC) pgpool cannot do peer authentication, it is probably this one, which says that all local (unix socket) connections will be authenticated by pretending the system username is the postgres username:
local all all peer
You want to change that to:
local all all trust
At least to make things work. However, you will lose some security this way. However, if all your users (that can access the unix socket) are trusted, this is okayish.