The button in the bottom right is coded into a widget released to instructors only.
This allows them to ask the d2l admins for help from within their course as well as the org homepage.
When the instructor completes the 'doorbell' request then the 2 admins receive an email and can reply directly. It also opens a ticket in doorbell until a response goes through. Replace variables can also be used to send through the originating course and username.