HA - pg_auto_failover for two node active-passive

Environment :
- Ubuntu 22.04, postgreSQL 14.18, OpenNMS Horizon 33.1.5-1,
- pg-auto-failover-cli, postgresql-auto-failover, all three nodes are SSH enabled
- keepalived (using different VIP)
- using RRD files at os
- lab setup - no data loss threat

Scenario :
Two node Active-Passive (postgresql 14 + opennms),
Third node Monitoring (multiple automatic failover/failback), no manual intervention
Floating IP (always refer active IP during failover/failback)

Architecture :
Serv1 - Active (postgresql 14, OpenNMS Horizon, pg-auto-failover-cli, postgresql-auto-failover)
Serv2 - Passive (postgresql 14, OpenNMS Horizon, pg-auto-failover-cli, postgresql-auto-failover)
Serv3 - Monitor (postgresql 14, pg-auto-failover-cli, postgresql-auto-failover)

Process :
1. enable Active-Passive
2. disable systemd of opennms for Serv2 (since active opennms will push data)
3. installed on Serv3 for monitor - pg-auto-failover-cli, postgresql-auto-failover
4. installed on Serv1, Serv2 for register - pg-auto-failover-cli, postgresql-auto-failover

Expectation :
- complete concise technical guide lines step-by-step in details (just to ensure of no missing step)
- challenges - now and then upgrade in minor versions for postgresql 14, opennms horizon which mismatch
configuration and functionality
- real-time sync of RRD files over LAN/WAN with no delay
- any better appropriate solution for multiple failover/failback without manual intervention or this will suffice and
serve the purpose

TIA