If you were using Office 2011 for Mac on an older operating system than Catalina, that 32-bit office suite is not compatible with Catalina which requires 64-bit applications. Your data is just fine though.
Microsoft no longer supports new installations of the current Microsoft 365 or Office 2021 for Mac suite on Catalina as they no longer support that operating system. That do currently support macOS 11, 12, and 13. You can use alternatives that are clones of MS Office, and for which your existing Office documents remain compatible: