If your Avira account differs from your address, you have to change the delivery address in the final step when placing your order.
Otherwise, you will have 2 different Avira accounts.
Your existing account, and the new account with the purchased license that uses the same email address as your PayPal account.
Change the delivery address
1. Proceed with your order as usual.
2. In the final step, change the "Delivery Address" to your existing Avira account email address.
Note
If you accidentally have 2 accounts, send an email to the Avira customer service with the request to merge 2 accounts. Write the email from the email address of the corresponding Avira account you wish to delete. Provide also the email address of the Avira account, you would like to keep.