The redirect URL you've specified when generating key&secret isn't matching your site URL, you need to delete old key&secret and generate new ones then enter new key&secret pair on your UNA site and go to the Apps Market > Storefront.
To delete old / keys you need enter to http://una.io -> Keys & Secrets area (available in your profile menu at the top-right corner). There you need to check old keys and press delete. Then add new key with proper url. In your UNA go to Studio->Settings->General. Enter there new key and secret and press "Save".
If you have purchased license then need to visit http://una.io -> Dashboard -> licenses, choose the actual one and reset it.