While you are logged in to your WordPress dashboard, you can navigate to any page on the front-end of your website and click the "Enable Visual Builder" button in the WordPress admin bar to launch the visual builder.
 
If you are editing your page on the back-end, you can switch to the visual builder by clicking the "Enable Visual Builder" button that sits at the top of the back-end Divi Builder interface (note, you must first enable the Divi Builder before the visual builder button will appear).
 
If you currently don't have the Divi Builder installed in your WordPress theme, contact support@xtendly.com, to discuss your upgrade options.