The switch UI should have a config or mgmt tab, under which should be a SNMP tab. Configure at least snmpv2c or v3.
Then in AirWave -> go to Device Setup -> Add -> select HPE OfficeConnect Switch, input the appropriate device creds, save/apply. Then when it gets to the monitoring tab -> it should take 1-2 manual polls for the device to report as up. Or you can wait for the automatic polling to resolve the status.
If this is still not working, please open a TAC case so that TAC can walk you through the process (it'll save you from having to read all the docs).