With the update to Mac OSX High Sierra (10.13.x) Apple have changed the default setup of all websites that use the Microsoft SilverLight adding. This change effectively disabled the website from accessing the local file system and causes the Admin Client to display an error dialog box.
To enable access to the file system the following instructions should be followed.
1. Open the Safari Preferences (Under the Safari Menu item)
2. Select the Websites tab, click on the Silverlight Plug-in and click on the sales.inzantsales.com entry in the Silverlight list.
3. Hold the Option key and click on the drop down selector in the list beside sales.inzantsales.com. If not already set to ON, change this to ON, also uncheck the Run in Safe Mode setting, as displayed below.
4. Turn off the Block pop-up windows setting, to allow reports to be generated for printing.
5. Quit Safari from the menu and restart Safari and load the Admin website again. The Application should now have access to the local file system.