Trouble Upgrading Postgres

I'd be grateful for some help. I am trying to move a large database from
PostgreSQL 9.6 on Centos 6 to a different server using PostgreSQL 11 on
Centos 7. I can't do a pg_dump because it always fails on the largest
table. So tried to do pb_basebackup and copy that to the new PG 11 server.
Except that pg_upgrade expects the new and old versions of PG to be
side-by-side. So I installed 9.6 on the new server, ran initdb, verified
that it started, then stopped it and edited postgresql.conf data path to
the location of the pg_basebackup files. Then 9.6 would no longer start. So
how can I get my PG 9.6 data into a new PG 11 database?

Probably related to my troubles are my attempts to get replication set up.
But before I dive back into that, I thought I'd better try getting my 9.6
data into the new 9.6 server, then run PG 11's pg_upgrade and mount the
data in PG 11. Then maybe I can get replication started.

I've read that logical replication can be used to migrate from 9.6 to 11,
but haven't found any documentation on doing that.

Chuck Martin