If your organization restricts the connections by IP address, you will need to whitelist the Kolleno IP address.
Company -> Overview -> Company Information
Click EDIT
Click on the ‘Security’ tab
Go to the field labeled “Enforce IP address filters” -> “Manage Filters” and click the Edit icon
Add the IP address 18.135.93.249 to the allowed list, and for the user select the WebService user you created previously.