To whom it may concerned,
This is the link of the starter pack with code, Under User Manager task, the video instructed to go to Messaging in the site and go to email and choose registration confirmation template for me to edit the email subject and email body but unfortunately, I cannot edit the email body as it still shows the warning that the email body is currently in read only mode and I do not have any more editor loads for this month, please see attach picture for the full snippet of the warning. Thank you!
Youtube video tutorial that I followed:
How to customize email confirmation template (youtube.com)