How do I add our support email address so it will display on my password reset emails from Cerberus?

In order for that to be displayed, you must enter an email address in the following section:

Go to Users > Requested Accounts (See screenshot below.)

Select 'Send approval notification emails' and enter your support email address in the 'Default Administrator Email' box

Click 'Update'

For emails to work, ensure you have added a SMTP setup in Event Targets (There must something to select in the 'Default Request Notification SMTP Server' field in the screenshot above). Instructions on that setup are here:

How do I setup SMTP to send Email notifications?