Microsoft supports the current release of macOS and the previous two releases for installation. Because macOS Monterey is outside of that criterion, you would need at minimum macOS Sonoma (14.*) or later.
If you do not have Apple's applications currently installed on Monterey, you cannot install the current versions from the Mac App Store as they now require macOS Sonoma (14.0) or later. Although there is a means to obtain the versions of these compatible¹ with Monterey, if they were preinstalled by Apple or a third-party, or you never installed them prior to Monterey, then you won't be able to now. Since Apple's applications are not clones of Microsoft applications, there is no guarantee that these applications can open and accurately convert Microsoft documents which may have feature or font incompatibilities.
The free LibreOffice has been under develop by one name or another ever since StarOffice in the 1990s. It has a high degree of MS Office document compatibility since it is a deliberate clone. There is a learning curve somewhat ameliorated by thorough documentation PDFs on their site. The current version of LIbreOffice wants macOS Big Sur (11.0) or later. Be careful to choose the correct download architecture for your Mac.
Softmaker has an Office suite that is a clone of MS Office and related document compatibility. Even the user interface is better than LibreOffice and SoftMaker's Office product is supported on Catalina and later. There is a short free trial, but is a paid application solution either as a single, or subscription purchase.
¹ One can launch the Mac App Store and sign in with the original Apple ID previously used to install Apple's applications. One then presses cmd+0 (zero) to open the past purchases screen, and if there are download indicators adjacent to Apple's Pages, Numbers, and Keynote, one can select these. There will be one or more screens where one does not click Cancel, and then a dialog asking to install the last compatible version of these applications for the current installed operating system. Click OK and it is done.