Instructors can view Enrollees who are enrolled in their Class(es). They can also see Enrollees' Account information. However, they can only manage Classes they are either assigned to or have all access to.
Add to Classes or Access All Classes
You will need to make sure the Instructor is added to the Class(es) on the Classes page. See this support article for how to add an Instructor to a Class. Instructors can also have access to all Classes. Just select the box "Can access all Classes" under Roles:
Manage Classes Permission
You will also need to make sure that within their Role, they have the permission "Manage Classes" (as seen below) selected so that they can edit Classes:
