Chimp-View requires that you request a licence, even if you are going to use the free tool, or try the free trial.
To do this, select the gear icon and select 'Payment'
In the payment section select the action you wish to perform.
If you select 'Purchase Chimp-View Pro' you will be taken to Davton's ecommerce site managed by Fastspring. When you have purchased your chosen licence, you will be sent a Licence-Key by email.
Use the 'Enter Licence-Key' option to enter the Licence-Key and your add-in will be fully functional.