Task 5You need to ensure that content on Microsoft SharePoint Online sites can be shared...

To ensure that content on Microsoft SharePoint Online sites can be shared only with new and existing guest users, you need to limit the external sharing settings in the SharePoint admin center. Here are the steps to follow:

Sign in to the SharePoint admin center with your admin credentials.

Go to  Policies   >   Sharing .

Under  External sharing , drag the  SharePoint  slider down to  New and existing guests . (The  OneDrive  slider is dependent on SharePoint and will also be set to  New and existing guests .)

Under  More external sharing settings , check the box  Allow only users in specific security groups to share externally  and select  Manage security groups .

Add the security groups that contain the users who are allowed to share content with guest users. You can also create a new security group if needed.

Click  Save  to apply the settings.