I do not know what special changes may have been made to the NAML code on your forum, but if no changes have been made the following should be true.
1. The groups that appear under the "People" menu are controlled via the "Change Permissions" permissions screen, accessed from:
Options > Users > Change permissions.
Set the "Show_group_members" permission for each group you want to display on the "People" list for that forum or sub-forum.
2. Concerning the missing mail: Check that the Option:
Options > Application > Extras & add-ons > Email & Notifications > Notify me when someone registers
is still checked.
3. Make sure you are logged-in with your Administrator Username to see the menu item:
Options > Users > Manage Users and Groups
That is where you can add or remove users from the "Members" group.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.