To setup alerts for new development projects in your area, you need to first create a portfolio of your assets. To do that please reference this article.
Once your portfolio is setup in Radius, simply select it from the Facility Management list and select the Balloon icon to turn on alerts.
By default you will receive an email alert if a new project pops up within 3 miles of one of your portfolio facilities. To change this to 1 mile or 5 miles you can navigate to the settings page and make that selection toward the bottom.