Postresql replication pg_basebackup no pg_hbaconf entry for replication connection
You have to grant access in replication in pg_hba.conf.
Here's the line you should add:

host    replication     replicator      10.0.2.15/32               trust


You will find documentation here:
https://www.postgresql.org/docs/9.6/static/auth-pg-hba-conf.html

Here's the phrase that explain everything:


  The value replication specifies that the record matches if a replication connection is requested (note that replication connections do not specify any particular database).