The weekly digest email is a NuORDER generated email containing important metrics and a breakdown of weekly activity for your brand. You can setup which users receive this email in your settings.
Head to brand Admin > Settings > Brand Settings
Scroll down to "Weekly Digest Email List"
Enter the emails of the users you'd like to add. Make sure they are added with no additional spaces between. They should be formatted like this, "email@example.com,firstname.lastname@example.org,email@example.com".
Make sure to scroll up and select "save" after you've entered all users.