pg_easy_replicate: Getting "Unable to check config: Unable to check superuser conditions: PG::ConnectionBad: FATAL: password authentication failed for user" in config_check

Hi! I am attempting to use this tool on a replication setup. It has worked fine for one database, but another has been nothing but trouble. I have created new superusers on each side, I have confirmed that I can login with psql to each of the URL setups on the same system as the pg_easy_replicate install. But this particular configuration always returns: Unable to check config: Unable to check superuser conditions: PG::ConnectionBad: FATAL: password authentication failed for user $USERNAME

Is there something I’m doing wrong in the setup? Thanks for your time.