Access to the requested resource is denied

Regarding this error message, please confirm the following...

1. Your Amazon Account must be a pro account. A personal account will not work.
2. Be sure you connect to the correct amazon account. If it is already connected, please try to click the Reconnect button in Settings  - Amazon Account.  When you connect it, please verify whether the account is correct or not, if it is not correct you must switch to use the correct Amazon account
3. Ensure your Amazon account has no red or orange alert
4. Your account must be Active
5. You can verify if your account is OK by trying to add a new product manually on your Amazon Seller Central account.