Before inviting members to a Unit, ensure those members are part of your organization. If not, invite members to your organizations and then follow this article to add them to Unit.
Ensure you are on the "Organizations" tab.
Select "Units".
Select the Unit you'd like to add members.
Tap "Manage".
Tap "+ Add".
Enter the name or email address of the member you're looking to add to the Unit.
Tap "Submit".
