Need Mac Numbers & Pages for Mojave
Running on Mojave, a quick test of deleting Pages reveals that I cannot download the latest version from the App Store's main pages, but if I go to the list of &quot;Purchased&quot; apps in my Account, I can download a compatible version.

If you haven't already purchased (for the sum of 0) the iWork apps, then you likely can't download them on older OSes. It's well worth downloading them now, for the future!