MicroSoft office for Mac version 11.7.10
What's the latest version of MS office that is comparable with OS Big Sur 11.7.10?
iMac 27″, macOS 11.7
See: Microsoft Support – Upgrade macOS to continue receiving Microsoft 365 and Office for Mac updates
Microsoft no longer supports any version of 365 or Office on Big Sur – and it sounds like new installations of 365 or Office 2024 require Ventura or later. If you are an existing customer, then you might be able to download an older, and now-unsupported, version of Office (see article).