Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi Sally McEnallay (Greenkit),
Thanks for posting in our forum. According to your description, do you mean that the error prompts when you try to save the "Let people outside the organization email the group" setting in Office 365 admin center?
Office 365 Admin center > Groups > select the new created group> Edit > enable "Let people outside the organization email the group" option > Save
If so, according to the error, please go to www.office.com > click the avatar on the upper right corner > My Account > Subscriptions > Check if you’ve assigned with the Exchange Online license. You can also provide us with the screenshot of the subscription page.
In addition, if it is a new created group, please wait for hours and try again to open your browser in incognito mode and check if the issue persists.
If the issue persists, you can also go to Exchange Admin center > recipients > groups > double click on the group > general > scroll down and tick the checkbox of ‘Let people outside the organization email the group’ > Save
Best Regards,
Huni