Steps to configure audit policy for Member Servers while adding, for already added Member Servers click on the "Configure" link in the 'Available Member Servers'[Configuration tab -> Configured Member Servers] table.
Login into ADAudit Plus
Click on "Configuration" Tab -->>"Configured Member Servers"
Click on "Add Member Servers" select the Server that require audit (This will list all the Member Servers on a Pop-up)
Select the Servers to be configured and click on "OK" (The below alert will be displayed).
Clicking on "Yes" will enable one or all of the below if not configured already.
Add the selected Member Servers for auditing.
"Audit LogonEvents" Policy will be enabled for the selected server via a GPO