Hi Kevin,
Greetings from ADManager Plus.
Seems like you've got the "most" of this. To get this working, we need a PowerShell script or a VB script that sends emails ---> create an automation with the Group Members Report and link this script, using the "Custom script" under Automate task/policy.
Unfortunately, we do not have a script to do exactly what you need but I do have a sample script that sends email with a body. I have it attached to this post.