If you want to make sure that you have Amazon Business account:
Log in your Amazon account with the help of your personal data (email and password).
After singing in, you should see the main page of your Amazon account. Pay your attention to the top of the navigation bar.
If you have Amazon Business account, you should see an “Amazon Business” or “Business Account” tab in the top of navigation bar. Click this bar to access Amazon Business features and tools.
If you don’t see this bar, it may mean that you don’t have an active Amazon Business account and your account is connected to a regular Amazon consumer.