To add external user manually do the following: Please be sure that the User is a part of SharePoint Visitors Group;
1. Go to LMS365 Admin Center.
2. Click the Learner List in the Learner Administration section.
3. Сlick Add User(s) button:
4. Type the names or email addresses in the search field:
5. Chose the required User from the dropdown.
6. Click Add button