Hi CSchumacher,

Thank you for posting in this community.

As RonBarker mentioned that Office 2021 Professional Plus is a volume licence and can only be legitimately provided by organizations.

So, in this case, you may Buy Office Home & Student 2021 instead.

According to this article: Buy Office Home & Student 2021 (PC or Mac) - Download & Pricing (microsoft.com)

We can notice that Office Home & Student 2021 is costs $149.99 on the Microsoft website.

According to this article: Manage your Microsoft 365 subscription purchased through a third party

If you purchased a Microsoft 365 subscription from a third-party retailer instead of the Microsoft Store, contact the third-party retailer directly to manage your subscription and billing.

• Microsoft has limited access and visibility over subscriptions purchased through a third-party retailer.
• Microsoft cannot cancel or help turn on or off recurring billing for subscriptions purchased through a third-party retailer.
• All refund requests must go to the third-party retailer from whom you purchased the subscription because Microsoft did not receive that payment. (This also applies to Office Home and Business licenses.)

And if you have a new, never used product key, you will need to go to www.office.com/setup and follow the on-screen prompts to redeem it to your account.

For your information: Using product keys with Office (microsoft.com)

If the Office product you purchased is not legitimate, you will not be able to redeem and use the product key.

So, in this situation, it’s recommended to purchase Office from Microsoft websites.

Best Regards,

May