1. Write the custom email template in html. Wherever you want the link to the user activation or reset password to be, just add an <a> html tag with the link "LINK".
An example html template is attached.
2. Upload the template to the correct S3 bucket in the ThingLogix root account.
The name of the files are important and have to be called:
forgot_email_template.txt (example in attached screenshot)