1. Sign in to Office 365 using your global admin or Exchange admin account. Browse to the Office 365 admin center. If you're not an admin, you can add or remove members using Outlook (https://support.office.com/en-us/article/add-and-remove-group-members-in-outlook-3b650f4a-5c9b-4f94-a1bb-0cca4b1091de).
2. In the left navigation pane, choose Groups > Groups.
3. Select a Group.
4. In the details pane, next to Members, click Edit.
5. Search for or select the name of the member you want to add.
6. Click Save.