pgpool replication not allowing md5 authentication
It looks like your default authentication mode for TCP/IP connections (host) is md5. So at a guess, you have PgPool connecting over TCP/IP.

Change the auth mode for loopback connections on tcp/ip, or use unix sockets with pgpool (usually by omitting the host setting).

If you're still stuck after reading:

19.1. The pg_hba.conf File and
Chapter 19. Client Authentication

in the PostgreSQL 9.4 documentation, and you can't find answers elsewhere (there are lots of related questions on Stack Overflow), let me know and I'll give you a step by step if I have a chance.