Hi!
Welcome to Microsoft Q&A forum.
Based on your screenshot you’ve created an Outlook.com group (consumer Outlook). You only see the very basic options (group name, description, picture). The settings that you need exists only in Microsoft 365 Groups managed through the Exchange Admin Center.
- Have full delivery management options.
- You can allow external senders.
and for that you’ll need a Microsoft 365 subscription (Business Basic, Standard, or higher).