Some older or stripped-down BMCs don't expose SNMP at all. ipmitool over the network (IPMI LAN) is the fallback Linivo's sensor can use instead.
Test connectivity from the sensor host before configuring the device in Linivo, so a credential problem doesn't get mistaken for a network one.
ipmitool -I lanplus -H 10.20.0.61 -U admin -P PASSWORD sdr list
In Devices > Add device, choose IPMI (LAN) instead of SNMP or Redfish, and supply the BMC's IP and credentials. Linivo shells out to ipmitool on the sensor to poll sensor readings on a schedule.
IPMI sensor data is typically less granular than Redfish's typed telemetry, mainly temperature, voltage, fan and power readings by sensor ID rather than named components. It's still enough to catch a failing fan or a PSU dropping out of redundancy.