With Microsoft now supporting Sonoma, Ventura, and Monterey, it has dropped support for new installations of any Office suite into Big Sur and older operating systems. Office 2019 for Mac was also retired on 2023-10-10. Thus, Microsoft has disabled the license servers for retired suites and unsupported macOS operating systems.
Here are the Macs compatible with:
macOS Monterey is compatible with these computers - Apple Support
macOS Ventura is compatible with these computers - Apple Support
macOS Sonoma is compatible with these computers - Apple Support
If in fact, you are stuck on Big Sur, then consider the free trial of Softmaker's Office 2024 for Mac as it is a faithfully supported MS Office clone that handles Microsoft documents in their native format. These are Universal binaries as I have it installed on my M2 mini Pro with Sonoma 14.1 — as well as Office 2021 for Mac.
Alternatively, there is the free LibreOffice Suite, which offers either of an Intel or Apple Silicon build for download.