Access-
You'll use your Microsoft account for everything you do with Microsoft 365 or www.office.com/setup. If you use a Microsoft service like Outlook, OneDrive, Xbox Live, or Skype, you already have an account. Sign in Create a new account.
Install Office for the first time and some office products come with a product key. If yours did, before installing Office for the first time, sign in with an existing or new Microsoft account and enter your product key at www.office.com/setup.
Locate the Office one-time purchase Office app, and then select www.office.com/setup to view your product key.
If you see the error means product key has already been used.
When you enter your product key on www.office.com/setup.
Go to microsoftstore.
Then, sign in with the Microsoft account that you used to buy Office.
Instead, use your Microsoft account to sign in to microsoft.
Then install your Office product.
This means your product key has already been redeemed and is no longer needed.
After you sign in, select your name and then select Order History.
Locate the Office one-time purchase or individual Office app.
And then select Install Office to view your product key.
Select Install Office again in the window where the product key appears.
Let's get started page.
Follow the prompts to sign in again and associate your product with your Microsoft account.