There are several places in Enrollsy where you can add internal notes that Admin users and Instructors can view.
Accounts Page
On an Account Holder's Account page, there is a place for internal notes. When you enter a note in this space, be sure you hit the "Save" button to save the message.
Any notes entered in the Account section can be viewed on the Enrollees Table under "Accounts."
Enrollee Page
On an Enrollee's page, there is a place for internal notes. When you enter a note in this space, be sure you hit the "Save" button to save the message.
Any notes entered in the Account section can be viewed on the Enrollees Table under "Enrollees" (or whatever you have called "Enrollees").
Billing Page
On the Account Billing page, only Admin users can enter and view internal billing notes. Be sure to click "Save" to save the message.
At this time, the internal billing notes cannot be viewed on the Enrollees Table. A workaround is to create your own internal enroll form field on the Account that is hidden from the Enroll Form and Customer Portal. See this article for steps.