Hi,
Need a guidance to create a memory and disk utilization alert for the respected group with a default threshold and share the trigger condition for the same
Here are a couple of KB articles to get you started.
This article lists the steps for creating an alert to trigger when a member of a group is down.
Success Center
Single alert when multiple devices go down in the Orion Platform
It is typically a lot easier to alert on resources based on a nodes custom property rather than alerting based on a group member. Alerting on groups is typically looking at the status of the group as a whole, not really on the individual group members.
-Greg Kjono
Loop1 Systems: SolarWinds Training and Professional Services