A family of Microsoft word processing software products for creating web, email, and print documents.
Apple's policy is to stop upgrading the OS on computers that are 9 to 10 years old. Microsoft's policy is to support Office for the three most recent versions of macOS. In effect, the combination of these policies forces users to keep buying new Macs to have access to the current edition of Office.
If you haven't been able to install Office, you can use the steps in this article to download, install and activate version 16.100: Most Recent Office You Can Run - Best Practices Your Microsoft 365 license works with that version, but you won't receive further updates. Fortunately, very little has changed with Office for Mac since the 16.100 edition was released.