The option was released in theme version 2.0.5

A theme and core plugin updates will be required – help to update http://help.wpresidence.net/article/how-to-update-the-theme/

Clear theme, plugin and browser cache after update to see the new mortgage calculator.

The mortgage calculator exists for Default Property Template and can be turned on/off from Theme Options -> Design -> Property Page Settings

You can enable these 2 fields to be managed for each property in Front End -> Submit Listing form

And these 2 values can be modified per property from wp-admin as well (Properties -> Edit Propeprty-> Property Details)