Older Version of Pages

Open the Mac App Store & hold down the option key while clicking the Purchases tab on your Mojave Mac. If you see Pages, Numbers, and Keynote with Update/Install buttons, it may offer to download a previous version of these applications compatible with Mojave.

If you have a Time Machine backup you might be able to restore the app from there.

In Mojave and later releases of macOS, one must enter ⌘+0 (zero) to get to the previous purchases panel in the Mac App Store. This changed from the option+Purchases tab in High Sierra and earlier.

Thanks, I'll try to remember that.

Knowing Apple, they will probably change it again to something entirely different…