My company has a production database on AWS RDS Postgres. We have been running into some replication problems regarding lag. We have adjusted the wal_keep_segments a few weeks ago and it has improved the overall replication lag but after a night with intensive writes we are getting some ocasional errors that I haven't really found documentation to enlighten what is this about:

archive /rdsdbdata/log/restore/pg-wal-archive.[some number].* is not yet downloaded, exiting restore script for now

I would appreciate any guidance regarding what this is related to and any documentation I can read about it.